Movable body drive method and movable body drive system, pattern formation method and apparatus, exposure method and apparatus, device manufacturing method, measuring method, and position measurement system

ABSTRACT

By moving a wafer stage while monitoring an XY position of a wafer stage WST using an interferometer system, and scanning a Y scale in an X-axis direction and a Y-axis direction using a surface position sensor, an XY setting position of the surface position sensor is measured. Based on information of the setting position obtained, by measuring a position coordinate of the wafer stage in a perpendicular direction with respect to an XY plane and a tilt direction, the wafer stage is driven in a stable manner and with high precision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of ProvisionalApplication No. 60/935,667 filed Aug. 24, 2007, the disclosure of whichis hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body drive methods and movablebody drive systems, pattern formation methods and apparatuses, exposuremethods and apparatuses, device manufacturing methods, measuringmethods, and position measurement systems, and more particularly, to amovable body drive method and a movable body drive system that drives amovable body along a substantially two-dimensional plane, a patternformation method using the movable body drive method and a patternformation apparatus equipped with the movable body drive system, anexposure method using the movable body drive method, and an exposureapparatus equipped with the movable body drive system, a devicemanufacturing method using the pattern formation method, a measuringmethod in which the positional information of a plurality of sensorheads equipped in a surface position measurement system that measure thepositional information of the movable body in a direction orthogonal tothe two-dimensional plane is measured, and a position measurement systemthat measures positional information of the movable body.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing electrondevices (microdevices) such as semiconductor devices (such as integratedcircuits) and liquid crystal display devices, exposure apparatuses suchas a projection exposure apparatus by a step-and-repeat method (aso-called stepper) and a projection exposure apparatus by astep-and-scan method (a so-called scanning stepper (which is also calleda scanner) are mainly used.

However, the surface of a wafer serving as a substrate subject toexposure is not always flat, for example, by undulation and the like ofthe wafer. Therefore, especially in a scanning exposure apparatus suchas a scanner and the like, when a reticle pattern is transferred onto ashot area on a wafer by a scanning exposure method, positionalinformation (focus information) related to an optical axis direction ofa projection optical system of the wafer surface is detected at aplurality of detection points set in an exposure area, for example,using a multiple point focal point position detection system(hereinafter also referred to as a “multipoint AF system”) and the like,and based on the detection results, a so-called focus leveling controlis performed (refer to, for example, U.S. Pat. No. 5,448,332) to controlthe position in the optical axis direction and the inclination of atable or a stage holding a wafer so that the wafer surface constantlycoincides with an image plane of the projection optical system in theexposure area (the wafer surface is within the focal depth of the imageplane).

Further, with the stepper or the scanner and the like, wavelength ofexposure light used with finer integrated circuits is becoming shorteryear by year, and numerical aperture of the projection optical system isalso gradually increasing (larger NA), which improves the resolution.Meanwhile, due to shorter wavelength of the exposure light and larger NAin the projection optical system, the depth of focus had becomeextremely small, which caused a risk of focus margin shortage during theexposure operation. Therefore, as a method of substantially shorteningthe exposure wavelength while substantially increasing (widening) thedepth of focus when compared with the depth of focus in the air, theexposure apparatus that uses the immersion method has recently begun togather attention (refer to, for example, the pamphlet of InternationalPublication No. 2004/053955).

However, in the exposure apparatus using this liquid immersion method orother exposure apparatus whose distance (working distance) between thelower end surface of the projection optical system and the wafer issmall, it is difficult to place the multipoint AF system in the vicinityof the projection optical system. Meanwhile, in the exposure apparatus,in order to realize exposure with high precision, realizing surfaceposition control of the wafer with high precision is required.

Further, with the stepper or the scanner or the like, positionmeasurement of the stage (the table) which holds a substrate (forexample, a wafer) subject to exposure was performed in general, using alaser interferometer having a high resolution. However, because theoptical path length of the laser interferometry beam which measures theposition of the stage is around several hundred mm or more, and alsobecause position control of the stage with higher precision is becomingrequired due to finer patterns owing to higher integration ofsemiconductor devices, short-term variation of measurement values whichis caused by air fluctuation which occurs due to the influence oftemperature fluctuation or temperature gradient of the atmosphere on thebeam path of the laser interferometer can no longer be ignored.

Accordingly, instead of the interferometer, it is conceivable that asensor system which directly measures positional information (surfaceposition information) of the surface of the table in the optical axisdirection is used, however, in such a system, there are various kinds ofcauses of error which are different from the interferometer.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda movable body drive method in which a movable body is drivensubstantially along a two-dimensional plane, the method comprising: adrive process in which the movable body is moved along a predetermineddirection parallel to the two-dimensional plane, and during the movementof the movable body, positional information of the movable body in adirection orthogonal to the two-dimensional plane is measured using aplurality of sensor heads of a position measurement system, and based onthe measurement information and positional information within a planeparallel to the two-dimensional plane of at least one sensor head usedin measurement of the information, the movable body is driven in atleast a tilt direction with respect to the two-dimensional plane.

According to this method, it becomes possible to drive the movable bodyin at least a tilt direction with respect to the two-dimensional planeso as to cancel out a position measurement error of the movable body inat least the tilt direction caused by a positional error (error from adesign value) of a sensor head within a surface parallel to thetwo-dimensional plane (the movement plane of the movable body).

According to a second aspect of the present invention, there is provideda pattern formation method, comprising: a mount process in which anobject is mounted on a movable body that can move along a movementplane; and a drive process in which the movable body is driven by themovable body drive method of the present invention, to form a pattern onthe object.

According to this method, because a movable body on which the object ismounted is driven with good accuracy by the movable body drive method inorder to form a pattern on an object, the pattern can be formed on theobject with good precision.

According to a third aspect of the present invention, there is provideda device manufacturing method including a pattern forming process,wherein in the pattern formation process, a pattern is formed on asubstrate using the pattern formation method of the present invention.

According to a fourth aspect of the present invention, there is providedan exposure method in which a pattern is formed on an object by anirradiation of an energy beam wherein for relative movement of theenergy beam and the object, a movable body on which the object ismounted is driven, using the movable body drive method of the presentinvention.

According to this method, for relative movement between an energy beamirradiated on the object and the object, the movable body on which theobject is mounted is driven with good precision, using the movable bodydrive method of the present invention. Accordingly, it becomes possibleto form a pattern on the object with good precision by scanningexposure.

According to a fifth aspect of the present invention, there is provideda measuring method in which positional information within a planeparallel to a two-dimensional plane of a sensor head, which is equippedin a position measurement system that measures positional information ina tilt direction with respect to the two-dimensional plane of a movablebody that moves along the two-dimensional plane and is used to measurepositional information of the movable body in a direction orthogonal tothe two-dimensional plane, is measured, the method comprising: a firsthead position measuring process in which the movable body is moved in afirst direction within the two-dimensional plane so that the movablebody passes through a detection area of a sensor corresponding to thesensor head of the position measurement system, and based on ameasurement value of a first measuring device arranged separately fromthe position measurement system and measures positional information ofthe movable body in the first direction and a detection signal of thesensor corresponding to the measurement value that are obtained duringthe movement, a position of the sensor head in the first direction iscomputed.

According to this method, only by moving the movable body in the firstdirection within the two-dimensional plane so that the movable bodypasses the detection area of the sensor corresponding to the sensor headof the position measurement system, the position in the first directionof the sensor head can be obtained.

According to a sixth aspect of the present invention, there is provideda movable body drive system in which a movable body is driven along asubstantially two-dimensional plane, the system comprising: a positionmeasurement system that has a plurality of heads which is placedtwo-dimensionally within a plane parallel to the two-dimensional planeand measures positional information of the movable body in a directionorthogonal to the two-dimensional plane; and a drive device that movesthe movable body along a predetermined direction parallel to thetwo-dimensional plane, and during the movement of the movable body,measures positional information of the movable body in the directionorthogonal to the two-dimensional plane using the plurality of sensorheads of the position measurement system, and based on the measurementinformation and positional information within a plane parallel to thetwo-dimensional plane of at least one sensor head used in measurement ofthe information, drives the movable body in a tilt direction withrespect to the two-dimensional plane.

According to this system, it becomes possible to drive the movable bodyin at least a tilt direction with respect to the two-dimensional planeso as to cancel out a position error of the movable body in at least thetilt direction caused by a positional error (error from a design value)of a sensor head within a surface parallel to the two-dimensional plane(the movement plane of the movable body).

According to a seventh aspect of the present invention, there isprovided a pattern formation apparatus, comprising: a movable body onwhich an object is mounted, and is movable along a movement planeholding the object, and a movable body drive system of the presentinvention which drives the movable body for pattern formation to theobject.

According to this apparatus, because the movable body which holds theobject is driven with good accuracy by the movable body drive system forpattern formation on an object, it becomes possible to form a pattern onan object with good precision.

According to an eighth aspect of the present invention, there isprovided an exposure apparatus that forms a pattern on an object by anirradiation of an energy beam, the apparatus comprising: a patterningdevice that irradiates the energy beam on the object; and a movable bodydrive system of the present invention, whereby the movable body drivesystem drives the movable body on which the object is mounted forrelative movement of the energy beam and the object.

According to this apparatus, for relative movement between the energybeam irradiated on the object and the object, drive with high precisionof the movable body on which the object is mounted is performed by themovable body drive system of the present invention. Accordingly, itbecomes possible to form a pattern on the object with good precision byscanning exposure.

According to a ninth aspect of the present invention, there is provideda position measurement system which measures positional information of amovable body that moves substantially along a two-dimensional plane, thesystem comprising: a plurality of sensor heads which are installed at aplurality of positions that can face the two-dimensional plane, facingthe movable body that moves substantially along the two-dimensionalplane and generating an output according to a position of the movablebody in a direction orthogonal to the two-dimensional plane, wherein atleast tilt information with respect to the two-dimensional plane of themovable body is detected, using an output from at least one of theplurality of sensor heads, and information related to a setting positionof the at least one sensor head on a plane substantially parallel to thetwo dimensional plane.

According to this system, from information related to the settingposition of the sensor head on the plane substantially parallel to thetwo-dimensional plane (the movement plane of the movable body), at leastthe tilt error of the movable body due to an error (an error from adesign value) of a setting position of the sensor head is obtained, andby deducting this tilt error, at least the tilt information with respectto the two-dimensional plane of the movable body can be obtained withgood precision.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings;

FIG. 1 is a view schematically showing the configuration of an exposureapparatus related to an embodiment;

FIG. 2 is a planar view showing a stage device in FIG. 1;

FIG. 3 is a planar view showing the placement of various measuringapparatuses (such as encoders, alignment systems, a multipoint AFsystem, and Z heads) that are equipped in the exposure apparatus in FIG.1;

FIG. 4A is a planar view showing a wafer stage, and FIG. 4B is aschematic side view of a partially sectioned wafer stage WST;

FIG. 5A is a planar view that shows a measurement stage MST, and FIG. 5Bis a partially sectioned schematic side view that shows measurementstage MST;

FIG. 6 is a block diagram showing a configuration of a control system ofthe exposure apparatus related to an embodiment;

FIG. 7 is a view schematically showing an example of a configuration ofa Z head;

FIG. 8A is a view showing an example of a focus sensor,

FIGS. 8B and 8C are views used to explain the shape and function of acylindrical lens in FIG. 8A;

FIG. 9A is a view showing a divided state of a detection area of atetrameric light receiving element, FIGS. 9B, 9C, and 9D are viewsrespectively showing a cross-sectional shape of reflected beam LB₂ on adetection surface in a front-focused, an ideal focus, and a back-focusedstate;

FIGS. 10A to 10C are views used to explain focus mapping performed inthe exposure apparatus related to an embodiment;

FIGS. 11A and 11B are views used to explain focus calibration performedin the exposure apparatus related to an embodiment;

FIGS. 12A and 12B are views used to explain offset correction among AFsensors performed in the exposure apparatus related to an embodiment;

FIG. 13 is a view showing a state of the wafer stage and the measurementstage where exposure to a wafer on the wafer stage is performed by astep-and-scan method;

FIG. 14 is a view showing a state of both stages at the time ofunloading of the wafer (when the measurement stage reaches the positionwhere Sec-BCHK (interval) is performed);

FIG. 15 is a view showing a state of both stages at the time of loadingof the wafer;

FIG. 16 is a view showing a state of both stages at the time ofswitching (when the wafer stage has moved to a position where the formerprocessing of Pri-BCHK is performed) from stage servo control by theinterferometer to stage servo control by the encoder;

FIG. 17 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three first alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 18 is a view showing a state of the wafer stage and the measurementstage when the former processing of focus calibration is beingperformed;

FIG. 19 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five second alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 20 is a view showing a state of the wafer stage and the measurementstage when at least one of the latter processing of Pri-BCHK and thelatter processing of focus calibration is being performed;

FIG. 21 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five third alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 22 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three fourth alignment shot areasare being simultaneously detected using alignment systems ALL, AL2 ₂ andAL2 ₃;

FIG. 23 is a view showing a state of the wafer stage and the measurementstage when the focus mapping has ended;

FIGS. 24A and 24B are views for explaining a computation method of the Zposition and the amount of tilt of wafer table WTB using the measurementresults of the Z heads;

FIGS. 25A and 25B are views showing a pattern for positioning of adiffraction grating plate arranged to measure a setting position of a Zhead; and

FIGS. 26A to 26C are views showing a pattern for explaining ameasurement of a setting position of a Z head using the pattern forpositioning of the diffraction grating plate.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described,referring to FIGS. 1 to 26.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 inthe embodiment. Exposure apparatus 100 is a scanning exposure apparatusof the step-and-scan method, namely the so-called scanner. As it will bedescribed later, a projection optical system PL is arranged in theembodiment, and in the description below, a direction parallel to anoptical axis AX of projection optical system PL will be described as theZ-axis direction, a direction within a plane orthogonal to the Z-axisdirection in which a reticle and a wafer are relatively scanned will bedescribed as the Y-axis direction, a direction orthogonal to the Z-axisand the Y-axis will be described as the X-axis direction, and rotational(inclination) directions around the X-axis, the Y-axis, and the Z-axiswill be described as θx, θy, and θz directions, respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST that holds a reticle R that is illuminated by anillumination light for exposure (hereinafter, referred to asillumination light, or exposure light) IL from illumination system 10, aprojection unit PU that includes projection optical system PL thatprojects illumination light IL emitted from reticle R on a wafer W, astage device 50 that has a wafer stage WST and a measurement stage MST,their control system, and the like. On wafer stage WST, wafer W ismounted.

Illumination system 10 includes a light source, an illuminanceuniformity optical system, which includes an optical integrator and thelike, and an illumination optical system that has a reticle blind andthe like (none of which are shown), as is disclosed in, for example,U.S. Patent Application Publication No. 2003/0025890 and the like.Illumination system 10 illuminates a slit-shaped illumination area IARwhich is set on reticle R with a reticle blind (a masking system) byillumination light (exposure light) IL with a substantially uniformilluminance. In this case, as illumination light IL, for example, an ArFexcimer laser beam (wavelength 193 nm) is used. Further, as the opticalintegrator, for example, a fly-eye lens, a rod integrator (an internalreflection type integrator), a diffractive optical element or the likecan be used.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivable ormovable in within an XY plane by a reticle stage drive section 11 (notshown in FIG. 1, refer to FIG. 6) that includes a linear motor or thelike, and reticle stage RST is also drivable in a scanning direction (inthis case, the Y-axis direction, which is the lateral direction of thepage surface in FIG. 1) at a designated scanning speed.

The positional information (including position (rotation) information inthe θz direction) of reticle stage RST in the XY plane (movement plane)is constantly detected, for example, at a resolution of around 0.25 nmby a reticle laser interferometer (hereinafter referred to as a “reticleinterferometer”) 116, via a movable mirror 15 (the mirrors actuallyarranged are a Y movable mirror (or a retro reflector) that has areflection surface which is orthogonal to the Y-axis and an X movablemirror that has a reflection surface orthogonal to the X-axis). Themeasurement values of reticle interferometer 116 are sent to a maincontroller 20 (not shown in FIG. 1, refer to FIG. 6). Main controller 20computes the position of reticle stage RST in the X-axis direction,Y-axis direction, and the θz direction based on the measurement valuesof reticle interferometer 116, and also controls the position (andvelocity) of reticle stage RST by controlling reticle stage drivesection 11 based on the computation results. Incidentally, instead ofmovable mirror 15, the edge surface of reticle stage RSV can be mirrorpolished so as to form a reflection surface (corresponding to thereflection surface of movable mirror 15). Further, reticleinterferometer 116 can measure positional information of reticle stageRST related to at least one of the Z-axis, θx, or θy directions.

Projection unit PU is placed below reticle stage RST in FIG. 1.Projection unit PU includes a barrel 40, and projection optical systemPL that has a plurality of optical elements which are held in apredetermined positional relation inside barrel 40. As projectionoptical system PL, for example, a dioptric system is used, consisting ofa plurality of lenses (lens elements) that is disposed along an opticalaxis AX, which is parallel to the Z-axis direction. Projection opticalsystem PL is, for example, a both-side telecentric dioptric system thathas a predetermined projection magnification (such as one-quarter,one-fifth, or one-eighth times). Therefore, when illumination light ILfrom illumination system 10 illuminates illumination area IAR, a reducedimage of the circuit pattern (a reduced image of a part of the circuitpattern) of the reticle is formed within illumination area IAR, withillumination light IL that has passed through reticle R which is placedso that its pattern surface substantially coincides with a first plane(an object plane) of projection optical system PL, in an area conjugateto illumination area IAR on wafer W (exposure area) whose surface iscoated with a resist (a photosensitive agent) and is placed on a secondplane (an image plane) side, via projection optical system PL(projection unit PU). And by reticle stage RST and wafer stage WST beingsynchronously driven, the reticle is relatively moved in the scanningdirection (the Y-axis direction) with respect to illumination area IAR(illumination light IL) while wafer W is relatively moved in thescanning direction (the Y-axis direction) with respect to the exposurearea (illumination light IL), thus scanning exposure of a shot area(divided area) on wafer W is performed, and the pattern of the reticleis transferred onto the shot area. That is, in the embodiment, thepattern is generated on wafer W according to illumination system 10, thereticle, and projection optical system PL, and then by the exposure ofthe sensitive layer (resist layer) on wafer W with illumination lightIL, the pattern is formed on wafer W.

Incidentally, although it is not shown, projection unit PU is installedin a barrel platform supported by three struts via a vibration isolationmechanism. However, as well as such a structure, as is disclosed in, forexample, the pamphlet of International Publication WO2006/038952 and thelike, projection unit PU can be supported by suspension with respect toa mainframe member (not shown) placed above projection unit PU or withrespect to a base member on which reticle stage RST is placed.

Incidentally, in exposure apparatus 100 of the embodiment, becauseexposure is performed applying a liquid immersion method, an opening onthe reticle side becomes larger with the substantial increase of thenumerical aperture NA. Therefore, in order to satisfy Petzval'scondition and to avoid an increase in size of the projection opticalsystem, a reflection/refraction system (a catodioptric system) which isconfigured including a mirror and a lens can be employed as a projectionoptical system. Further, in wafer W, in addition to a sensitive layer (aresist layer), for example, a protection film (a topcoat film) or thelike which protects the wafer or a photosensitive layer can also beformed.

Further, in exposure apparatus 100 of the embodiment, in order toperform exposure applying the liquid immersion method, a nozzle unit 32that constitutes part of a local liquid immersion device 8 is arrangedso as to enclose the periphery of the lower end portion of barrel 40that holds an optical element that is closest to an image plane side(wafer W side) that constitutes projection optical system PL, which is alens (hereinafter, also referred to a “tip lens”) 191 in this case. Inthe embodiment, as shown in FIG. 1, the lower end surface of nozzle unit32 is set to be substantially flush with the lower end surface of tiplens 191. Further, nozzle unit 32 is equipped with a supply opening anda recovery opening of liquid Lq, a lower surface to which wafer W isplaced facing and at which the recovery opening is arranged, and asupply flow channel and a recovery flow channel that are connected to aliquid supply pipe 31A and a liquid recovery pipe 31B respectively.Liquid supply pipe 31A and liquid recovery pipe 31B are slanted byaround 45 degrees relative to an X-axis direction and Y-axis directionin a planar view (when viewed from above) as shown in FIG. 3, and areplaced symmetric to a straight line (a reference axis) LV which passesthrough the center (optical axis AX of projection optical system PL,coinciding with the center of exposure area IA previously described inthe embodiment) of projection unit PU and is also parallel to theY-axis.

One end of a supply pipe (not shown) is connected to liquid supply pipe31A while the other end of the supply pipe is connected to a liquidsupply unit 5 (not shown in FIG. 1, refer to FIG. 6), and one end of arecovery pipe (not shown) is connected to liquid recovery pipe 31B whilethe other end of the recovery pipe is connected to a liquid recoverydevice 6 (not shown in FIG. 1, refer to FIG. 6).

Liquid supply device 5 includes a liquid tank for supplying liquid, acompression pump, a temperature controller, a valve for controllingsupply/stop of the liquid to liquid supply pipe 31A, and the like. Asthe valve, for examples a flow rate control valve is preferably used sothat not only the supply/stop of the liquid but also the adjustment offlow rate can be performed. The temperature controller adjusts thetemperature of the liquid within the tank, for example, to nearly thesame temperature as the temperature within the chamber (not shown) wherethe exposure apparatus is housed. Incidentally, the tank, thecompression pump, the temperature controller, the valve, and the like donot all have to be equipped in exposure apparatus 100, and at least partof them can also be substituted by the equipment or the like availablein the plant where exposure apparatus 100 is installed.

Liquid recovery device 6 includes a liquid tank for collecting liquid, asuction pump, a valve for controlling recovery/stop of the liquid vialiquid recovery pipe 31B, and the like. As the valve, it is desirable touse a flow control valve similar to the valve of liquid supply device 5.Incidentally, the tank, the suction pump, the valve, and the like do notall have to be equipped in exposure apparatus 100, and at least part ofthem can also be substituted by the equipment or the like available inthe plant where exposure apparatus 100 is installed.

In the embodiment, as liquid Lq described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 nm) is to be used. Pure water can beobtained in large quantities at a semiconductor manufacturing plant orthe like without difficulty, and it also has an advantage of having noadverse effect on the photoresist on the wafer, to the optical lenses orthe like.

Refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shorted to around 134 nm.

Liquid supply device 5 and liquid recovery device 6 each have acontroller, and the respective controllers are controlled by maincontroller 20 (refer to FIG. 6). According to instructions from maincontroller 20, the controller of liquid supply device 5 opens the valveconnected to liquid supply pipe 31A to a predetermined degree to supplyliquid (water) to the space between tip lens 191 and wafer W via liquidsupply pipe 31A, the supply flow channel and the supply opening.Further, when the water is supplied, according to instructions from maincontroller 20, the controller of liquid recovery device 6 opens thevalve connected to liquid recovery pipe 31B to a predetermined degree torecover the liquid (water) from the space between tip lens 191 and waferW into liquid recovery device 6 (the liquid tank) via the recoveryopening, the recovery flow channel and liquid recovery pipe 31B. Duringthe supply and recovery operations, main controller 20 gives commands tothe controllers of liquid supply device 5 and liquid recovery device 6so that the quantity of water supplied to the space between tip lens 191and wafer W constantly equals the quantity of water recovered from thespace. Accordingly, a constant quantity of liquid (water) Lq (refer toFIG. 1) is held in the space between tip lens 191 and wafer W. In thiscase, liquid (water) Lq held in the space between tip lens 191 and waferW is constantly replaced.

As is obvious from the above description, in the embodiment, localliquid immersion device 8 is configured including nozzle unit 32, liquidsupply device 5, liquid recovery device 6, liquid supply pipe 31A andliquid recovery pipe 31B, and the like. Incidentally, part of localliquid immersion device 8, for example, at least nozzle unit 32 may alsobe supported in a suspended state by a main frame (including the barrelplatform) that holds projection unit PU, or may also be arranged atanother frame member that is separate from the main frame. Or, in thecase projection unit PU is supported in a suspended state as isdescribed earlier, nozzle unit 32 may also be supported in a suspendedstate integrally with projection unit PU, but in the embodiment, nozzleunit 32 is arranged on a measurement frame that is supported in asuspended state independently from projection unit PU. In this case,projection unit PU does not have to be supported in a suspended state.

Incidentally, also in the case measurement stage MST is located belowprojection unit PU, the space between a measurement table (to bedescribed later) and tip lens 191 can be filled with water in thesimilar manner to the manner described above.

Incidentally, in the description above, one liquid supply pipe (nozzle)and one liquid recovery pipe (nozzle) were arranged as an example,however, the present invention is not limited to this, and aconfiguration having multiple nozzles as is disclosed in, for example,the pamphlet of International Publication No. 99/49504, may also beemployed, in the case such an arrangement is possible taking intoconsideration a relation with adjacent members. The point is that anyconfiguration can be employed, as long as the liquid can be supplied inthe space between optical member (tip lens) 191 in the lowest endconstituting projection optical system PL and wafer W. For example, theliquid immersion mechanism disclosed in the pamphlet of InternationalPublication No. 2004/053955, or the liquid immersion mechanism disclosedin the EP Patent Application Publication No. 1 420 298 can also beapplied to the exposure apparatus of the embodiment.

Referring back to FIG. 1, stage device 50 is equipped with a wafer stageWST and a measurement stage MST placed above a base board 12, ameasurement system 200 (refer to FIG. 6) which measures positionalinformation of the stages WST and MST, a stage drive system 124 (referto FIG. 6) which drives stages WST and MST and the like. Measurementsystem 200 includes an interferometer system 118, an encoder system 150,and a surface position measurement system 180 and the like as shown inFIG. 6. Incidentally, details on interferometer system 118, encodersystem 150 and the like will be described later in the description.

Referring back to FIG. 1, on the bottom surface of each of wafer stageWST and measurement stage MST, a noncontact bearing (not shown), forexample, a vacuum preload type hydrostatic air bearing (hereinafter,referred to as an “air pad”) is arranged at a plurality of points, andwafer stage WST and measurement stage MST are supported in a noncontactmanner via a clearance of around several μm above base board 12, bystatic pressure of pressurized air that is blown out from the air padtoward the upper surface of base board 12. Further, stages WST and MSTare drivable independently within the XY plane, by stage drive system124 (refer to FIG. 6) which includes a linear motor and the like.

Wafer stage WST includes a stage main section 91, and a wafer table WTBthat is mounted on stage main section 91. Wafer table WTB and stage mainsection 91 are configured drivable in directions of six degrees offreedom (X, Y, Z, θx, θy, and θz) with respect to base board 12 by adrive system including a linear motor and a Z leveling mechanism(including a voice coil motor and the like).

On wafer table WTB, a wafer holder (not shown) that holds wafer W byvacuum suction or the like is arranged. The wafer holder may also beformed integrally with wafer table WTB, but in the embodiment, the waferholder and wafer table WTB are separately configured, and the waferholder is fixed inside a recessed portion of wafer table WTB, forexample, by vacuum suction or the like. Further, on the upper surface ofwafer table WTB, a plate (liquid repellent plate) 28 is arranged, whichhas the surface (liquid repellent surface) substantially flush with thesurface of wafer W mounted on the wafer holder to which liquid repellentprocessing with respect to liquid Lq is performed, has a rectangularouter shape (contour), and has a circular opening that is formed in thecenter portion and is slightly larger than the wafer holder (a mountingarea of the wafer). Plate 28 is made of materials with a low coefficientof thermal expansion, such as glass or ceramics (e.g., such as Zerodur(the brand name) of Schott AG, Al₂O₃, or TiC) and on the surface ofplate 28, a liquid repellent film is formed by, for example, fluorineresin materials, fluorine series resin materials such aspolytetrafluoroethylene (Teflon (registered trademark)), acrylic resinmaterials, or silicon series resin materials. Further, as shown in aplaner view of wafer table WTB (wafer stage WST) in FIG. 4A, plate 28has a first liquid repellent area 28 a whose outer shape (contour) isrectangular enclosing a circular opening, and a second liquid repellentarea 28 b that has a rectangular frame (annular) shape placed around thefirst liquid repellent area 28 a. On the first liquid repellent area 28a, for example, at the time of an exposure operation, at least part of aliquid immersion area 14 (refer to FIG. 13) that is protruded from thesurface of the wafer is formed, and on the second liquid repellent area28 b, scales for an encoder system (to be described later) are formed.Incidentally, at least part of the surface of plate 28 does not have tobe on a flush surface with the surface of the wafer, that is, may have adifferent height from that of the surface of the wafer. Further, plate28 may be a single plate, but in the embodiment, plate 28 is configuredby combining a plurality of plates, for example, the first and secondliquid repellent plates that correspond to the first liquid repellentarea 28 a and the second liquid repellent area 28 b respectively. In theembodiment, water is used as liquid Lq as is described above, andtherefore, hereinafter the first liquid repellent area 28 a and thesecond liquid repellent area 28 b are also referred to as a first waterrepellent plate 28 a and a second water repellent plate 28 b.

In this case, exposure light IL is irradiated to the first waterrepellent plate 28 a on the inner side, while exposure light IL ishardly irradiated to the second water repellent plate 28 b on the outerside. Taking this fact into consideration, in the embodiment, a firstwater repellent area to which water repellent coat having sufficientresistance to exposure light IL (light in a vacuum ultraviolet region,in this case) is applied is formed on the surface of the first waterrepellent plate 28 a, and a second water repellent area to which waterrepellent coat having resistance to exposure light IL inferior to thefirst water repellent area is applied is formed on the surface of thesecond water repellent plate 28 b. In general, since it is difficult toapply water repellent coat having sufficient resistance to exposurelight IL (in this case, light in a vacuum ultraviolet region) to a glassplate, it is effective to separate the water repellent plate into twosections, the first water repellent plate 28 a and the second waterrepellent plate 28 b which is the periphery of the first water repellentplate, in the manner described above. Incidentally, the presentinvention is not limited to this, and two types of water repellent coatthat have different resistance to exposure light IL may also be appliedon the upper surface of the same plate in order to form the first waterrepellent area and the second water repellent area. Further, the samekind of water repellent coat may be applied to the first and secondwater repellent areas. For example, only one water repellent area mayalso be formed on the same plate.

Further, as is obvious from FIG. 4A, at the end portion on the +Y sideof the first water repellent plate 28 a, a rectangular cutout is formedin the center portion in the X-axis direction, and a measurement plate30 is embedded inside the rectangular space (inside the cutout) that isenclosed by the cutout and the second water repellent plate 28 b. Afiducial mark FM is formed in the center in the longitudinal directionof measurement plate 30 (on a centerline LL of wafer table WTB), and apair of aerial image measurement slit patterns (slit-shaped measurementpatterns) SL are formed in the symmetrical placement with respect to thecenter of the fiducial mark on one side and the other side in the X-axisdirection of the fiducial mark. As each of aerial image measurement slitpatterns SL, an L-shaped slit pattern having sides along the Y-axisdirection and X-axis direction, or two linear slit patterns extending inthe X-axis and Y-axis directions respectively can be used, as anexample.

Further, as is shown in FIG. 4B, inside wafer stage WST below each ofaerial image measurement slit patterns SL, an L-shaped housing 36 inwhich an optical system containing an objective lens, a mirror, a relaylens and the like is housed is attached in a partially embedded statepenetrating through part of the inside of wafer table WTB and stage mainsection 91. Housing 36 is arranged in pairs corresponding to the pair ofaerial image measurement slit patterns SL, although omitted in thedrawing.

The optical system inside housing 36 guides illumination light IL thathas been transmitted through aerial image measurement slit pattern SLalong an L-shaped route and emits the light toward a −Y direction.Incidentally, in the following description, the optical system insidehousing 36 is described as a light-transmitting system 36 by using thesame reference code as housing 36 for the sake of convenience.

Moreover, on the upper surface of the second water repellent plate 28 b,multiple grid lines are directly formed in a predetermined pitch alongeach of four sides. More specifically, in areas on one side and theother side in the X-axis direction of second water repellent plate 28 b(both sides in the horizontal direction in FIG. 4A), Y scales 39Y₁ and39Y₂ are formed respectively, and Y scales 39Y₁ and 39Y₂ are eachcomposed of a reflective grating (for example, a diffraction grating)having a periodic direction in the Y-axis direction in which grid lines38 having the longitudinal direction in the X-axis direction are formedin a predetermined pitch along a direction parallel to the Y-axis (theY-axis direction).

Similarly, in areas on one side and the other side in the Y-axisdirection of second water repellent plate 28 b (both sides in thevertical direction in FIG. 4A), X scales 39X₁ and 39X₂ are formedrespectively in a state where the scales are placed between Y scales39Y₁ and 39Y₂, and X scales 39X₁ and 39X₂ are each composed of areflective grating (for example, a diffraction grating) having aperiodic direction in the X-axis direction in which grid lines 37 havingthe longitudinal direction in the Y-axis direction are formed in apredetermined pitch along a direction parallel to the X-axis (the X-axisdirection). As each of the scales, a scale is used that has a reflectivediffraction grating made by, for example, hologram or the like, on thesurface of the second water repellent plate 28 b. In this case, eachscale has gratings made up of narrow slits, grooves or the like that aremarked at a predetermined distance (pitch) as graduations. The type ofdiffraction grating used for each scale is not limited, and not only thediffraction grating made up of grooves or the like that are mechanicallyformed, but also, for example, the diffraction grating that is createdby exposing interference fringe on a photosensitive resin may be used.However, each scale is created by marking the graduations of thediffraction grating, for example, in a pitch between 138 nm to 4 μm, forexample, a pitch of 1 μm on a thin plate shaped glass. These scales arecovered with the liquid repellent film (water repellent film) describedabove. Incidentally, the pitch of the grating is shown much wider inFIG. 4A than the actual pitch, for the sake of convenience. The same istrue also in other drawings.

In this manner, in the embodiment, since the second water repellentplate 28 b itself constitutes the scales, a glass plate with low-thermalexpansion is to be used as the second water repellent plate 28 b.However, the present intention is not limited to this, and a scalemember made up of a glass plate or the like with low-thermal expansionon which a grating is formed may also be fixed on the upper surface ofwafer table WTB, for example, by a plate spring (or vacuum suction) orthe like so as to prevent local shrinkage/expansion. In this case, awater repellent plate to which the same water repellent coat is appliedon the entire surface may be used instead of plate 28. Or, wafer tableWTB may also be formed by materials with a low coefficient of thermalexpansion, and in such a case, a pair of Y scales and a pair of X scalesmay be directly formed on the upper surface of wafer table WTB.

Incidentally, in order to protect the diffraction grating, it is alsoeffective to cover the grating with a glass plate with low thermalexpansion that has water repellency (liquid repellency). In this case,as the glass plate, a plate whose thickness is the same level as thewafer, such as for example, a plate 1 mm thick, can be used, and theplate is set on the upper surface of wafer table WST so that the surfaceof the glass plate becomes the same height (a flush surface) as thewafer surface.

Incidentally, a lay out pattern is arranged for deciding the relativeposition between an encoder head and a scale near the edge of each scale(to be described later). The lay out pattern is configured, for example,from grid lines that have different reflectivity, and when the encoderhead scans the pattern, the intensity of the output signal of theencoder changes. Therefore, a threshold value is determined beforehand,and the position where the intensity of the output signal exceeds thethreshold value is detected. Then, the relative position between theencoder head and the scale is set, with the detected position as areference.

Further, to the −Y edge surface and the −X edge surface of wafer tableWTB, mirror-polishing is applied, respectively, and as shown in FIG. 2,a reflection surface 17 a and a reflection surface 17 b are formed forinterferometer system 118 which will be described later in thedescription.

Measurement stage MST includes a stage main section 92 driven in the XYplane by a linear motor and the like (not shown), and a measurementtable MTB mounted on stage main section 92, as shown in FIG. 1.Measurement stage MST is configured drivable in at least directions ofthree degrees of freedom (X, Y, and θz) with respect to base board 12 bya drive system (not shown).

Incidentally, the drive system of wafer stage WST and the drive systemof measurement stage MST are included in FIG. 6, and are shown as stagedrive system 124.

Various measurement members are arranged at measurement table MTB (andstage main section 92). As such measurement members, for example, asshown in FIGS. 2 and 5A, members such as an uneven illuminance measuringsensor 94 that has a pinhole-shaped light-receiving section whichreceives illumination light IL on an image plane of projection opticalsystem PL, an aerial image measuring instrument 96 that measures anaerial image (projected image) of a pattern projected by projectionoptical system PL, a wavefront aberration measuring instrument 98 by theShack-Hartman method that is disclosed in, for example, the pamphlet ofInternational Publication No. 2003/065428 and the like are employed. Aswavefront aberration measuring instrument 98, the one disclosed in, forexample, the pamphlet of International Publication No. 99/60361 (thecorresponding EP Patent No. 1 079 223) can also be used.

As irregular illuminance sensor 94, the configuration similar to the onethat is disclosed in, for example, U.S. Pat. No. 4,465,368 and the like,can be used. Further, as aerial image measuring instrument 96, theconfiguration similar to the one that is disclosed in, for example, U.S.Patent Application Publication No. 2002/0041377 and the like can beused. Incidentally, in the embodiment, three measurement members (94, 96and 98) were to be arranged at measurement stage MST, however, the typeof the measurement member and/or the number is not limited to them. Asthe measurement members, for example, measurement members such as atransmittance measuring instrument that measures a transmittance ofprojection optical system PL, and/or a measuring instrument thatobserves local liquid immersion unit 8, for example, nozzle unit 32 (ortip lens 191) or the like may also be used. Furthermore, membersdifferent from the measurement members such as a cleaning member thatcleans nozzle unit 32, tip lens 191 or the like may also be mounted onmeasurement stage MST.

In the embodiment, as can be seen from FIG. 5A, the sensors that arefrequently used such as irregular illuminance sensor 94 and aerial imagemeasuring instrument 96 are placed on a centerline CL (Y-axis passingthrough the center) of measurement stage MST. Therefore, in theembodiment, measurement using these sensors can be performed by movingmeasurement stage MST only in the Y-axis direction without moving themeasurement stage in the X-axis direction.

In addition to each of the sensors described above, an illuminancemonitor that has a light-receiving section having a predetermined areasize that receives illumination light IL on the image plane ofprojection optical system PL may also be employed, which is disclosedin, for example, U.S. Patent Application Publication No. 2002/0061469and the like. The illuminance monitor is also preferably placed on thecenterline.

Incidentally, in the embodiment, liquid immersion exposure is performedin which wafer W is exposed with exposure light (illumination light) ILvia projection optical system PL and liquid (water) Lq, and accordinglyirregular illuminance sensor 94 (and the illuminance monitor), aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are used in measurement using illumination light ILreceive illumination light IL via projection optical system PL andwater. Further, only part of each sensor such as the optical system maybe mounted on measurement table MTB (and stage main section 92), or theentire sensor may be placed on measurement table MTB (and stage mainsection 92).

Further, on the +Y edge surface and the +X edge surface of measurementtable MTB, reflection surfaces 19 a and 19 b are formed similar to wafertable WTB previously described (refer to FIGS. 2 and 5A).

As shown in FIG. 5B, a frame-shaped attachment member 42 is fixed to theend surface on the −Y side of stage main section 92 of measurement stageMST. Further, to the end surface on the −Y side of stage main section92, a pair of photodetection systems 44 are fixed in the vicinity of thecenter position in the X-axis direction inside an opening of attachmentmember 42, in the placement capable of facing a pair oflight-transmitting systems 36 described previously. Each ofphotodetection systems 44 is composed of an optical system such as arelay lens, a light receiving element such as a photomultiplier tube,and a housing that houses them. As is obvious from FIGS. 4B and 5B andthe description so far, in the embodiment, in a state where wafer stageWST and measurement stage MST are closer together within a predetermineddistance in the Y-axis direction (including a contact state),illumination light IL that has been transmitted through each aerialimage measurement slit pattern SL of measurement plate 30 is guided byeach light-transmitting system 36 and received by the light-receivingelement of each photodetection system 44. That is, measurement plate 30,light-transmitting systems 36 and photodetection systems 44 constitutean aerial image measuring unit 45 (refer to FIG. 6), which is similar tothe one disclosed in, U.S. Patent Application Publication No.2002/0041377 referred to previously, and the like.

On attachment member 42, a fiducial bar (hereinafter, shortly referredto as an “FD bar”) which is made up of a bar-shaped member hating arectangular sectional shape is arranged extending in the X-axisdirection. FD bar 46 is kinematically supported on measurement stage MSTby a full-kinematic mount structure.

Since FD bar 46 serves as a prototype standard (measurement standard),optical glass ceramics with a low coefficient of thermal expansion, suchas Zerodur (the brand name) of Schott AG are employed as the materials.The flatness degree of the upper surface (the surface) of FD bar 46 isset high to be around the same level as a so-called datum plane plate.Further, as shown in FIG. 5A, a reference grating (for example, adiffraction grating) 52 whose periodic direction is the Y-axis directionis respectively formed in the vicinity of the end portions on one sideand the other side in the longitudinal direction of FD bar 46. The pairof reference gratings 52 is formed placed apart from each other at apredetermined distance symmetric to the center in the X-axis directionof FD bar 46, or more specifically, formed in a symmetric placement tocenterline CL previously described.

Further, on the upper surface of FD bar 46, a plurality of referencemarks M are formed in a placement as shown in FIG. 5A. The plurality ofreference marks M are formed in three-row arrays in the Y-axis directionin the same pitch, and the array of each row is formed being shiftedfrom each other by a predetermined distance in the X-axis direction. Aseach of reference marks M, a two-dimensional mark having a size that canbe detected by a primary alignment system and secondary alignmentsystems (to be described later) is used. Reference mark M may also bedifferent in shape (constitution) from fiducial mark FM, but in theembodiment, reference mark M and fiducial mark FM have the sameconstitution and also they have the same constitution with that of analignment mark of wafer W. Incidentally, in the embodiment, the surfaceof FD bar 46 and the surface of measurement table MTB (which may includethe measurement members described above) are also covered with a liquidrepellent film (water repellent film) severally.

In exposure apparatus 100 of the embodiment, although it is omitted inFIG. 1 from the viewpoint of avoiding intricacy of the drawing, as shownin FIG. 3, a primary alignment system AL1 having a detection center at aposition spaced apart from optical axis AX of projection optical systemPL at a predetermined distance on the −Y side is actually placed onreference axis LV. Primary alignment system AL1 is fixed to the lowersurface of a main frame (not shown) via a support member 54. On one sideand the other side in the X-axis direction with primary alignment systemAL1 in between, secondary alignment systems AL2 ₁ and AL2 ₂, and AL2 ₃and AL2 ₄ whose detection centers are substantially symmetrically placedwith respect to straight line LV are severally arranged. That is, fivealignment systems AL1 and AL2 ₁ to AL2 ₄ are placed so that theirdetection centers are placed at different positions in the X-axisdirection, that is, placed along the X-axis direction.

As is representatively shown by secondary alignment system AL2 ₄, eachsecondary alignment system AL2 _(n) (n=1 to 4) is fixed to a tip(turning end) of an arm 56 _(n) (n=1 to 4) that can turn around arotation center O as the center in a predetermined angle range inclockwise and anticlockwise directions in FIG. 3. In the embodiment, apart of each secondary alignment system AL2 _(n) (e.g. including atleast an optical system that irradiates an alignment light to adetection area and also leads the light that is generated from a subjectmark within the detection area to a light-receiving element) is fixed toarm 56 and the remaining section is arranged at the main frame thatholds projection unit PU. The X-positions of secondary alignment systemsAL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are severally adjusted by rotating aroundrotation center O as the center. In other words, the detection areas (orthe detection centers) of secondary alignment systems AL2 ₁, AL2 ₂, AL2₃ and AL2 ₄ are independently movable in the X-axis direction.Accordingly, the relative positions of the detection areas of primaryalignment system AL1 and secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃and AL2 ₄ are adjustable in the X-axis direction. Incidentally, in theembodiment, the X-positions of secondary alignment systems AL2 ₁, AL2 ₂,AL2 ₃ and AL2 ₄ are to be adjusted by the rotation of the arms. However,the present invention is not limited to this, and a drive mechanism thatdrives secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ backand forth in the X-axis direction may also be arranged. Further, atleast one of secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄can be moved not only in the X-axis direction but also in the Y-axisdirection.

Incidentally, since part of each secondary alignment system AL2 _(n) ismoved by arm 56 _(n), positional information of the part that is fixedto arm 56 _(n) is measurable by a sensor (not shown) such as, forexample, an interferometer or an encoder. The sensor may only measureposition information in the X-axis direction of secondary alignmentsystem AL2 _(n), or may also be capable of measuring positioninformation in another direction, for example, the Y-axis directionand/or the rotation direction (including at least one of the θx and θydirections).

On the upper surface of each arm 56 _(n), a vacuum pad 58 _(n) (n=1 to4, not shown in FIG. 3, refer to FIG. 6) that is composed of adifferential evacuation type air bearing is arranged. Further, arm 56_(n) can be turned by a rotation drive mechanism 60 _(n) (n=1 to 4, notshown in FIG. 3, refer to FIG. 6) that includes, for example, a motor orthe like, in response to instructions of main controller 20. Maincontroller 20 activates each vacuum pad 58 _(n) to fix each arm 56 _(n)to a main frame (not shown) by suction after rotation adjustment of arm56 _(n). Thus, the state of each arm 56 _(n) after rotation angleadjustment, that is, a desired positional relation between primaryalignment system AL1 and four secondary alignment systems AL2 ₁ to AL2 ₄is maintained.

Incidentally, in the case a portion of the main frame facing arm 56 _(n)is a magnetic body, an electromagnet may also be employed instead ofvacuum pad 58.

In the embodiment, as each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄, for example, an FIA (FieldImage Alignment) system by an image processing method is used thatirradiates a broadband detection beam that does not expose resist on awafer to a subject mark, and picks up an image of the subject markformed on a light-receiving plane by the reflected light from thesubject mark and an image of an index (an index pattern on an indexplate arranged within each alignment system) (not shown), using animaging device (such as CCD), and then outputs their imaging signals.The imaging signal from each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄ is supplied to maincontroller 20 in FIG. 6, via an alignment signal processing system (notshown).

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (e.g. diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed. Further, in theembodiment, five alignment systems AL1 and AL2 ₁ to AL2 ₄ are to befixed to the lower surface of the main frame that holds projection unitPU, via support member 54 or arm 56 _(n). However, the present inventionis not limited to this, and for example, the five alignment systems mayalso be arranged on the measurement frame described earlier.

Next, a configuration and the like of interferometer system 118 (referto FIG. 6), which measures the positional information of wafer stage WSTand measurement stage MST, will be described.

The measurement principle of the interferometer will now be brieflydescribed, prior to describing a concrete configuration of theinterferometer system. The interferometer irradiates a measurement beam(measurement light) on a reflection surface set at a measurement object.The interferometer receives a synthesized light of the reflected lightand a reference beam, and measures the intensity of interference light,which is the reflected light (measurement light) and the reference beammade to interfere with each other, with their polarized directionsarranged. In this case, due to optical path difference ΔL of thereflected light and the reference beam, the relative phase (phasedifference) between the reflected light and the reference beam changesby KΔL. Accordingly, the intensity of the interference light changes inproportion to 1+a·cos(KΔL). In this case, homodyne detection is to beemployed, and the wave number of the measurement light and the referencebeam is the same, expressed as K. Constant a is decided by the intensityratio of the measurement light and the reference beam. In this case, thereflection surface to the reference beam is arranged generally on theprojection unit PU side surface (in some cases, inside theinterferometer unit). The reflection surface of this reference beambecomes the reference position of the measurement. Accordingly, inoptical path difference ΔL, the distance from the reference position tothe reflection surface is reflected. Therefore, if the number of times(the number of fringes) of intensity change of the interference lightwith respect to the change of distance to the reflection surface ismeasured, displacement of the reflection surface provided in themeasurement object can be computed by the product of a counter value anda measurement unit. The measurement unit, in the case of aninterferometer of a single-pass method is half the wavelength of themeasurement light, and in the case of an interferometer of thedouble-pass method, one-fourth of the wavelength.

Now, in the case an interferometer of the heterodyne detection method isemployed, wave number K₁ of the measurement light and wave number K₂ ofthe reference beam are slightly different. In this case, when theoptical path length of the measurement light and the reference beam isL₁ and L₂, respectively, the phase difference between the measurementbeam and the reference beam is given KΔL+ΔKL₁, and the intensity of theinterference light changes in proportion to 1+a·cos(KΔL+ΔKL₁). In thiscase, optical path difference ΔL=L₁−L₂, ΔK=K₁−K₂, and K=K₂. When opticalpath length L₂ of the reference beam is sufficiently short, andapproximate ΔL≈L₁ stands, the intensity of the interference lightchanges in proportion to 1+a·cos [(K+ΔK) ΔL]—As it can be seen fromabove, the intensity of the interference light periodically vibrates ata wavelength 2π/K of the reference beam along with the change of opticalpath difference ΔL, and the envelope curve of the periodic vibrationvibrates (beats) at a long cycle 2π/ΔK. Accordingly, in the heterodynedetection method, the changing direction of optical path difference ΔL,or more specifically, the displacement direction of the measurementobject can be learned from the long-period beat.

Incidentally, as a major cause of error of the interferometer, theeffect of temperature fluctuation (air fluctuation) of the atmosphere onthe beam optical path can be considered. Assume that wavelength λ of thelight changes to λ+Δλ by air fluctuation. Because the change of phasedifference KΔL by minimal change Δλ of the wavelength is wave numberK=2π/λ, 2πΔLΔλ/λ² can be obtained. In this case, when wavelength oflight λ=1 um and minimal change Δλ=1 nm, the phase change becomes 2π×100with respect to an optical path difference ΔL=100 mm. This phase changecorresponds to displacement which is 100 times the measurement unit. Inthe case the optical path length which is set is long as is described,the interferometer is greatly affected by the air fluctuation whichoccurs in a short time, and is inferior in short-term stability. In sucha case, it is desirable to use a surface position measurement systemwhich will be described later that has an encoder or a Z head.

Interferometer system 118 includes a Y interferometer 16, Xinterferometers 126, 127, and 128, and Z interferometers 43A and 43B forposition measurement of wafer stage WST, and a Y interferometer 18 andan X interferometer 130 for position measurement of measurement stageMST, as shown in FIG. 2. By severally irradiating a measurement beam onreflection surface 17 a and reflection surface 17 b of water table WTBand receiving a reflected light of each beam, Y interferometer 16 and Xinterferometers 126, 127, and 128 (X interferometers 126 to 128 are notshown in FIG. 1, refer to FIG. 2) measure a displacement of eachreflection surface from a reference position (for example, a fixedmirror is placed on the side surface of projection unit PU, and thesurface is used as a reference surface), or more specifically, measurethe positional information of wafer stage WST within the XY plane, andthe positional information that has been measured is supplied to maincontroller 20. In the embodiment, as it will be described later on, aseach interferometer a multiaxial interferometer that has a plurality ofmeasurement axes is used with an exception for a part of theinterferometers.

Meanwhile, to the side surface on the −Y side of stage main section 91,a movable mirror 41 having the longitudinal direction in the X-axisdirection is attached via a kinematic support mechanism (not shown), asshown in FIGS. 4A and 4B. Movable mirror 41 is made of a member which islike a rectangular solid member integrated with a pair of triangularprisms adhered to a surface (the surface on the −Y side) of therectangular solid member. As it can be seen from FIG. 2, movable mirror41 is designed so that the length in the X-axis direction is longer thanreflection surface 17 a of wafer table WTB by at least the spacingbetween the two Z interferometers which will be described later.

To the surface on the −Y side of movable mirror 41, mirror-polishing isapplied, and three reflection surfaces 41 b, 41 a, and 41 c are formed,as shown in FIG. 4B. Reflection surface 41 a configures a part of theedge surface on the −Y side of movable mirror 41, and reflection surface41 a is parallel with the XZ plane and also extends in the X-axisdirection. Reflection surface 41 b configures a surface adjacent toreflection surface 41 a on the +Z side, forming an obtuse angle toreflection surface 41 a, and spreading in the X-axis direction.Reflection surface 41 c configures a surface adjacent to the −Z side ofreflection surface 41 a, and is arranged symmetrically with reflectionsurface 41 b, with reflection surface 41 b in between.

A pair of Z interferometers 43A and 43B (refer to FIGS. 1 and 2) thatirradiates measurement beams on movable mirror 41 is arranged facingmovable mirror 41.

As it can be seen when viewing FIGS. 1 and 2 together, Z interferometers43A and 43B are placed apart on one side and the other side of Yinterferometer 16 in the X-axis direction at a substantially equaldistance and at positions slightly lower than Y interferometer 16,respectively.

From each of the Z interferometers 43A and 43B, as shown in FIG. 1,measurement beam B1 along the Y-axis direction is irradiated towardreflection surface 41 b, and measurement beam B2 along the Y-axisdirection is irradiated toward reflection surface 41 c (refer to FIG.4B). In the embodiment, fixed mirror 47B having a reflection surfaceorthogonal to measurement beam B1 reflected off reflection surface 41 band a fixed mirror 47A having a reflection surface orthogonal tomeasurement beam B2 reflected off reflection surface 41 c are arranged,each extending in the X-axis direction at a position distanced apartfrom movable mirror 41 in the −Y-direction by a predetermined distancein a state where the fixed mirrors do not interfere with measurementbeams B1 and B2

Fixed mirrors 47A and 47B are supported, for example, by the samesupport body (not shown) arranged in the frame (not shown) whichsupports projection unit PU.

Y interferometer 16, as shown in FIG. 2 (and FIG. 13), irradiatesmeasurement beams B4 ₁ and B4 ₂ on reflection surface 17 a of wafertable WTB along a measurement axis in the Y-axis direction spaced apartby an equal distance to the −X side and the +X side from reference axisLV previously described, and by receiving each reflected light, detectsthe position of wafer table WTB in the Y-axis direction (a Y position)at the irradiation point of measurement beams B4 ₁ and B4 ₂.Incidentally, in FIG. 1, measurement beams B4 ₁ and B4 ₂ arerepresentatively shown as measurement beam B4.

Further, Y interferometer 16 irradiates a measurement beam B3 towardreflection surface 41 a along a measurement axis in the Y-axis directionwith a predetermined distance in the Z-axis direction spaced betweenmeasurement beams B4 ₂ and B4 ₂, and by receiving measurement beam B3reflected off reflection surface 41 a, detects the Y position ofreflection surface 41 a (more specifically wafer stage WST) of movablemirror 41.

Main controller 20 computes the Y position (or to be more precise,displacement Δ Y in the Y-axis direction) of reflection surface 17 a, ormore specifically, wafer table WTB (wafer stage WST), based on anaverage value of the measurement values of the measurement axescorresponding to measurement beams B4 ₁ and B4 ₂ of Y interferometer 16.Further, main controller 20 computes displacement (yawing amount)Δθz^((Y)) of wafer stage WST in the rotational direction around theZ-axis (the θz direction), based on a difference of the measurementvalues of the measurement axes corresponding to measurement beams B4 ₁and B4 ₂. Further, main controller 20 computes displacement (pitchingamount) Δθx in the θx direction of wafer stage WST, based on the Yposition (displacement ΔY in the Y-axis direction) of reflection surface17 a and reflection surface 41 a.

Further, as shown in FIGS. 2 and 13, X interferometer 126 irradiatesmeasurement beams B5 ₁ and B5 ₂ on wafer table WTB along the dualmeasurement axes spaced apart from a straight line (a reference axis) LHin the X-axis direction that passes the optical axis of projectionoptical system PL by the same distance. And, based on the measurementvalues of the measurement axes corresponding to measurement beams B5 ₁and B5 ₂, main controller 20 computes a position (an X position, or tobe more precise, displacement ΔX in the X-axis direction) of wafer stageWST in the X-axis direction. Further, main controller 20 computesdisplacement (yawing amount) ΔθZ^((X)) of wafer stage WST in the θzdirection from a difference of the measurement values of the measurementaxes corresponding to measurement beams B5 ₁ and B5 ₂. Incidentally,Δθz_((X)) obtained from X interferometer 126 and Δθz^((Y)) obtained fromY interferometer 16 are equal to each other, and represents displacement(yawing amount) Δθz of wafer stage WST in the θz direction.

Further, as shown in FIGS. 14 and 15, a measurement beam B7 from Xinterferometer 128 is irradiated on reflection surface 17 b of wafertable WTB along a straight line LUL, which is a line connecting anunloading position UP where unloading of the wafer on wafer table WTB isperformed and a loading position LP where loading of the wafer ontowafer table WTB is performed and is parallel to the X-axis. Further, asshown in FIGS. 16 and 17, a measurement beam B6 from X interferometer127 is irradiated on reflection surface 17 b of wafer table WTB along astraight line (a reference axis) LA, which passes through the detectioncenter of primary alignment system AL1 and is parallel to the X-axis.

Main controller 20 can obtain displacement ΔX of wafer stage WST in theX-axis direction from the measurement values of measurement beam B6 of Xinterferometer 127 and the measurement values of measurement beam 37 ofX interferometer 128. However, the placement of the three Xinterferometers 126, 127, and 128 is different in the Y-axis direction.Therefore, X interferometer 126 is used at the time of exposure as shownin FIG. 13, X interferometer 127 is used at the time of wafer alignmentas shown in FIG. 19, and X interferometer 128 is used at the time ofwafer loading shown in FIG. 15 and wafer unloading shown in FIG. 14.

From Z interferometers 43A and 43B previously described, measurementbeams B1 and 32 that proceed along the Y-axis are irradiated towardmovable mirror 41, respectively, as shown in FIG. 1. These measurementbeams B1 and B2 are incident on reflection surfaces 41 b and 41 c ofmovable mirror 41, respectively, at a predetermined angle of incidence(the angle is to be θ/2). Then, measurement beam B1 is sequentiallyreflected by reflection surfaces 41 b and 41 c, and then is incidentperpendicularly on the reflection surface of fixed mirror 47B, whereasmeasurement beam B2 is sequentially reflected by reflection surfaces 41c and 41 b and is incident perpendicularly on the reflection surface offixed mirror 47A. Then, measurement beams B2 and B1 reflected off thereflection surface of fixed mirrors 47A and 47B are sequentiallyreflected by reflection surfaces 41 b and 41 c again, or aresequentially reflected by reflection surfaces 41 c and 41 b again(returning the optical path at the time of incidence oppositely), andthen are received by Z interferometers 43A and 43B.

In this case, when displacement of movable mirror 41 (more specifically,wafer stage WST) in the Z-axis direction is ΔZo and displacement in theY-axis direction is ΔYo, an optical path length change ΔL₁ ofmeasurement beam B1 and an optical path length change ΔL₂ of measurementbeam B2 can respectively be expressed as in formulas (1) and (2) below.ΔL1=ΔYo×(1+cos θ)+ΔZo×sin θ  (1)ΔL2=ΔYo×(1+cos θ)−ΔZo×sin θ  (2)

Accordingly, from formulas (1) and (2), ΔZo and ΔYo can be obtainedusing the following formulas (3) and (4).ΔZo=(ΔL1−ΔL2)/2 sin θ  (3)ΔYo=(ΔL1+ΔL2)/{2(1+cos θ)}  (4)

Displacements ΔZo and ΔYo above can be obtained with Z interferometers43A and 43B. Therefore, displacement which is obtained using zinterferometer 43A is to be ΔZoR and Δ YoR, and displacement which isobtained using Z interferometer 43B is to be ΔZoL and ΔYoL. And thedistance between measurement beams B1 and B2 irradiated by Zinterferometers 43A and 43B, respectively, in the X-axis direction is tobe a distance D (refer to FIG. 2). Under such premises, displacement(yawing amount) Δθz of movable mirror 41 (more specifically, wafer stageWST) in the θz direction and displacement (rolling amount) Δθy in the θydirection can be obtained by the following formulas (5) and (6).Δθz=tan⁻¹{(ΔYoR−ΔYoL)/D}  (5)Δθy=tan⁻¹{(ΔZoL−ΔZoR)/D}  (6)

Accordingly, by using the formulas (3) to (6) above, main controller 20can compute displacement of wafer stage WST in four degrees of freedom,ΔZo, ΔYo, Δθz, and Δθy, based on the measurement results of Zinterferometers 43A and 43B.

In the manner described above, from the measurement results ofinterferometer system 118, main controller 20 can obtain displacement ofwafer stage WST in directions of six degrees of freedom (Z, X, Y, θz,θx, and θy directions).

Incidentally, in the embodiment, a single stage which can be driven insix degrees of freedom was employed as wafer stage WST, however, insteadof this, wafer stage WST can be configured including a stage mainsection 91, which is freely movable within the XY plane, and a wafertable WTB, which is mounted on stage main section 91 and is finelydrivable relatively with respect to stage main section 91 in at leastthe Z-axis direction, the θx direction, and the θy direction, or a waferstage WST can be employed that has a so-called coarse and fine movementstructure where wafer table WTB can be configured finely movable in theX-axis direction, the Y-axis direction, and the θz direction withrespect to stage main section 91. However, in this case, a configurationin which positional information of wafer table WTB in directions of sixdegree of can be measured by interferometer system 118 will have to beemployed. Also for measurement stage MST, the stage can be configuredsimilarly, by a stage main section 92, and a measurement table MTB,which is mounted on stage main section 91 and has three degrees offreedom or six degrees of freedom. Further, instead of reflectionsurface 17 a and reflection surface 17 b, a movable mirror consisting ofa plane mirror can be arranged in wafer table WTB.

In the embodiment, however, position information within the XY plane(including the rotation information in the θz direction) for positioncontrol of wafer stage WST (wafer table WTB) is mainly measured by anencoder system (to be described later), and the measurement values ofinterferometers 16, 126, and 127 are secondarily used in cases such aswhen long-term fluctuation (for example, by temporal deformation or thelike of the scales) of the measurement values of the encoder system iscorrected (calibrated).

Incidentally, at least part of interferometer system 118 (such as anoptical system) may be arranged at the main frame that holds projectionunit PU, or may also be arranged integrally with projection unit PU thatis supported in a suspended state as is described above, however, in theembodiment, interferometer system 118 is to be arranged at themeasurement frame described above.

Incidentally, in the embodiment, positional information of wafer stageWST was to be measured with a reflection surface of a fixed mirrorarranged in projection unit PU serving as a reference surface, however,the position to place the reference surface at is not limited toprojection unit PU, and the fixed mirror does not always have to be usedto measure the positional information of wafer stage WST.

Further, in the embodiment, positional information of wafer stage WSTmeasured by interferometer system 118 is not used in the exposureoperation and the alignment operation which will be described later on,and was mainly to be used in calibration operations (more specifically,calibration of measurement values) of the encoder system, however, themeasurement information (more specifically, at least one of thepositional information in directions of five degrees of freedom) ofinterferometer system 118 can be used in the exposure operation and/orthe alignment operation. Further, using interferometer system 118 as abackup of an encoder system can also be considered, which will beexplained in detail later on. In the embodiment, the encoder systemmeasures positional information of wafer stage WST in directions ofthree degrees of freedom, or more specifically, the X-axis, the Y-axis,and the θz direction. Therefore, in the exposure operation and the like,of the measurement information of interferometer system 118, positionalinformation related to a direction that is different from themeasurement direction (the X-axis, the Y-axis, and the θz direction) ofwafer stage WST by the encoder system, such as, for example, positionalinformation related only to the θx direction and/or the θy direction canbe used, or in addition to the positional information in the differentdirection, positional information related to the same direction (morespecifically, at least one of the X-axis, the Y-axis, and the θzdirections) as the measurement direction of the encoder system can alsobe used. Further, in the exposure operation and the like, the positionalinformation of wafer stage WST in the Z-axis direction measured usinginterferometer system 118 can be used.

In addition, interferometer system 118 (refer to FIG. 6) includes a Yinterferometer 18 and an X interferometer 130 for measuring thetwo-dimensional position coordinates of measurement table MTB. Yinterferometer 18 and X interferometer 130 (X interferometer 130 is notshown in FIG. 1, refer to FIG. 2) irradiate measurement beams onreflection surfaces 19 a and 19 b of measurement table MTB as shown inFIG. 2, and measure the displacement from a reference position of eachreflection surface by receiving the respective reflected lights. Maincontroller 20 receives the measurement values of Y interferometer 18 andX interferometer 130, and computes the positional information (forexample, including at least the positional information in the X-axis andthe Y-axis directions and rotation information in the θz direction) ofmeasurement stage MST.

Incidentally, as the Y interferometer used for measuring measurementtable MTB, a multiaxial interferometer which is similar to Yinterferometer 16 used for measuring wafer stage WST can be used.Further, as the X interferometer used for measuring measurement tableMTB, a two-axis interferometer which is similar to X interferometer 126used for measuring wafer stage WST can be used. Further, in order tomeasure Z displacement, Y displacement, yawing amount, and rollingamount of measurement stage MST, interferometers similar to zinterferometers 43A and 43B used for measuring wafer stage WST can beintroduced.

Next, the structure and the like of encoder system 150 (refer to FIG. 6)which measures positional information (including rotation information inthe θz direction) of wafer stage WST in the XY plane will be described.

In exposure apparatus 100 of the embodiment, as shown in FIG. 3, fourhead units 62A to 62D of encoder system 150 are placed in a state ofsurrounding nozzle unit 32 on all four sides. In actual, head units 62Ato 62D are fixed to the foregoing main frame that holds projection unitPU in a suspended state via a support member, although omitted in thedrawings such as FIG. 3 from the viewpoint of avoiding intricacy of thedrawings.

As shown in FIG. 3, head units 62A and 62C are placed on the +X side andthe −X side of projection unit PU, with the X-axis direction serving asa longitudinal direction. Head units 62A and 62C are each equipped witha plurality of (five, in this case) Y heads 65 _(i) and 64 _(j) (i,j=1-5) that are placed at a distance WD in the X-axis direction. Moreparticularly, head units 62A and 62C are each equipped with a pluralityof (four, in this case) Y heads (64 ₁ to 64 ₄ or 65 ₂ to 655) that areplaced on straight line (reference axis) LH which passes through opticalaxis AX of projection optical system PL and is also parallel to theX-axis at distance WD except for the periphery of projection unit PU,and a Y head (64 ₅ or 65 ₁) which is placed at a position apredetermined distance away in the −Y-direction from reference axis LHin the periphery of projection unit PU, or more specifically, on the −Yside of nozzle unit 32. Head units 62A and 62C are each also equippedwith five Z heads which will be described later on. Hereinafter, Y heads65 _(j) and 64 _(i) will also be described as Y heads 65 and 64,respectively, as necessary.

Head unit 62A constitutes a multiple-lens (five-lens, in this case) Ylinear encoder (hereinafter appropriately shortened to “Y encoder” or“encoder”) 70A (refer to FIG. 6) that measures the position of waferstage WST (wafer table WTB) in the Y-axis direction (the Y-position)using Y scale 39Y₁ previously described. Similarly, head unit 62Cconstitutes a multiple-lens (five-lens, in this case) Y linear encoder70C (refer to FIG. 6) that measures the Y-position of wafer stage WSTusing Y scale 39Y₂ described above. In this case, distance WD in theX-axis direction of the five Y heads (64 _(i) or 65 _(j)) (morespecifically, measurement beams) that head units 62A and 62C are eachequipped with, is set slightly narrower than the width (to be moreprecise, the length of grid line 38) of Y scales 39Y₁ and 39Y₂ in theX-axis direction.

As shown in FIG. 3, head unit 62B is placed on the +Y side of nozzleunit 32 (projection unit PU), and is equipped with a plurality of, inthis case, four X heads 66 ₅ to 66 ₈ that are placed on reference axisLV along Y-axis direction at distance WD. Further, head unit 62D isplaced on the −Y side of primary alignment system AL1, on the oppositeside of head unit 62B via nozzle unit 32 (projection unit PU), and isequipped with a plurality of, in this case, four X heads 66 ₁ to 66 ₄that are placed on reference axis LV at distance WD. Hereinafter, Xheads 66 ₁ to 66 ₈ will also be described as X head 66, as necessary.

Head unit 62B constitutes a multiple-lens (four-lens, in this case) Xlinear encoder (hereinafter, shortly referred to as an “X encoder” or an“encoder” as needed) 705 (refer to FIG. 6) that measures the position inthe X-axis direction (the X-position) of wafer stage WST using X scale39X₁ described above. Further, head unit 62D constitutes a multiple-lens(four-lens, in this case) X encoder 70D (refer to FIG. 6) that measuresthe X-position of wafer stage WST using X scale 39X₂ described above.

Here, the distance between adjacent X heads 66 (measurement beams) thatare equipped in each of head units 62B and 62D is set shorter than awidth in the Y-axis direction of X scales 39X₁ and 39X₂ (to be moreaccurate, the length of grid line 37). Further, the distance between Xhead 66 ₅ of head unit 62B farthest to the −Y side and X head 66 ₄ ofhead unit 62D farthest to the +Y side is set slightly narrower than thewidth of wafer stage WST in the Y-axis direction so that switching(linkage described below) becomes possible between the two X heads bythe movement of wafer stage WST in the Y-axis direction.

In the embodiment, furthermore, head units 62F and 62E are respectivelyarranged a predetermined distance away on the −Y side of head units 62Aand 62C. Although illustration of head units 62E and 62F is omitted inFIG. 3 and the like from the viewpoint of avoiding intricacy of thedrawings, in actual practice, head units 62E and 62F are fixed to theforegoing main frame that holds projection unit PU in a suspended statevia a support member. Incidentally, for example, in the case projectionunit PU is supported in a suspended state, head units 62E and 62F, andhead units 62A to 62D which are previously described can be supported ina suspended state integrally with projection unit PU, or can be arrangedat the measurement frame described above.

Head unit 62E is equipped with four Y heads 67 ₁ to 67 ₄ whose positionsin the X-axis direction are different. More particularly, head unit 62Eis equipped with three Y heads 67 ₁ to 67 ₃ placed on the −X side of thesecondary alignment system AL2 ₁ on reference axis LA previouslydescribed at substantially the same distance as distance WD previouslydescribed, and one Y head 67 ₄ which is placed at a position apredetermined distance (a distance slightly shorter than WD) away on the+X side from the innermost (the +X side) Y head 67 ₃ and is also on the+Y side of the secondary alignment system AL2 ₁ a predetermined distanceaway to the +Y side of reference axis LA.

Head unit 62F is symmetrical to head unit 62E with respect to referenceaxis LV, and is equipped with four Y heads 68 ₁ to 68 ₄ which are placedin symmetry to four Y heads 67 ₁ to 67 ₄ with respect to reference axisLV. Hereinafter, Y heads 67 ₁ to 67 ₄ and 68 ₁ to 68 ₄ will also bedescribed as Y heads 67 and 68, respectively, as necessary. In the caseof an alignment operation and the like which will be described later on,at least one each of Y heads 67 and 68 faces Y scale 39Y₂ and 39Y₁,respectively, and by such Y heads 67 and 68 (more specifically, Yencoders 70E and 70F which are configured by these Y heads 67 and 68),the Y position (and the θz rotation) of wafer stage WST is measured.

Further, in the embodiment, at the time of baseline measurement(Sec−BCHK (interval)) and the like of the secondary alignment system AL2₁ which will be described later on, Y head 67 ₃ and 68 ₂ which areadjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in theX-axis direction face the pair of reference gratings 52 of FD bar 46,respectively, and by Y heads 67 ₃ and 68 ₂ that face the pair ofreference gratings 52, the Y position of FD bar 46 is measured at theposition of each reference grating 52. In the description below, theencoders configured by Y heads 67 ₃ and 68 ₂ which face the pair ofreference gratings 52, respectively, are referred to as Y linearencoders (also shortly referred to as a “Y encoder” or an “encoder” asneeded) 70E2 and 70F2. Further, for identification, Y encoders 70E and70F configured by Y heads 67 and 68 that face Y scales 39Y₂ and 39Y₁described above, respectively, will be referred to as Y encoders 70E1and 70F1.

The encoders 70A to 70F described above measure the position coordinatesof wafer stage WST at a resolution of, for example, around 0.1 nm, andthe measurement values are supplied to main controller 20. Maincontroller 20 controls the position within the XY plane of water stageWST based on three measurement values of linear encoders 70A to 70D oron three measurement values of encoders 70B, 70D, 70E₁ and 70F₁, andalso controls the rotation in the θz direction of FD bar 46 based on themeasurement values of linear encoders 70E₂ and 70F₂. Incidentally, theconfiguration and the like of the linear encoder will be describedfurther later in the description.

In exposure apparatus 100 of the embodiment, as shown in FIG. 3, amultipoint focal position detecting system (hereinafter, shortlyreferred to as a “multipoint AF system”) by an oblique incident methodis arranged, which is composed of an irradiation system 90 a and aphotodetection system 90 b, having a configuration similar to the onedisclosed in, for example, U.S. Pat. No. 5,448,332 and the like. In theembodiment, as an example, irradiation system 90 a is placed on the +Yside of the −X end portion of head unit 62E previously described, andphotodetection system 90 b is placed on the +Y side of the +X endportion of head unit 62F previously described in a state opposingirradiation system 90 a.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected. In the embodiment, the plurality of detectionpoints are placed, for example, in the arrangement of a matrix havingone row and M columns (M is a total number of detection points) orhaving two rows and N columns (N is a half of a total number ofdetection points). In FIG. 3, the plurality of detection points to whicha detection beam is severally irradiated are not individually shown, butare shown as an elongate detection area (beam area) AF that extends inthe X-axis direction between irradiation system 90 a and photodetectionsystem 90 b. Since the length of detection area AF in the X-axisdirection is set to around the same as the diameter of wafer W, positioninformation (surface position information) in the Z-axis directionacross the entire surface of wafer W can be measured by only scanningwafer W in the Y-axis direction once. Further, since detection area AFis placed between liquid immersion area 14 (exposure area IA) and thedetection areas of the alignment systems (AL1, AL2 ₁ to AL2 ₄) in theY-axis direction, the detection operations of the multipoint AF systemand the alignment systems can be performed in parallel. The multipointAF system may also be arranged on the main frame that holds projectionunit PU or the like, however, in the embodiment, the system will bearranged on the measurement frame previously described.

Incidentally, the plurality of detection points are to be placed in onerow and M columns, or two rows and N columns, but the number(s) of rowsand/or columns is/are not limited to these numbers. However, in the casethe number of rows is two or more, the positions in the X-axis directionof detection points are preferably made to be different between thedifferent rows. Moreover, the plurality of detection points is to beplaced along the X-axis direction. However, the present invention is notlimited to this, and all of or some of the plurality of detection pointsmay also be placed at different positions in the Y-axis direction. Forexample, the plurality of detection points may also be placed along adirection that intersects both of the X-axis and the Y-axis. That is,the positions of the plurality of detection points only have to bedifferent at least in the X-axis direction. Further, a detection beam isto be irradiated to the plurality of detection points in the embodiment,but a detection beam may also be irradiated to, for example, the entirearea of detection area AF. Furthermore, the length of detection area AFin the X-axis direction does not have to be nearly the same as thediameter of wafer W.

In the vicinity of detection points located at both ends out of aplurality of detection points of the multipoint AF system (90 a, 90 b),that is, in the vicinity of both end portions of beam area AF, heads 72a and 72 b, and 72 c and 72 d of surface position sensors for Z positionmeasurement (hereinafter, shortly referred to as “Z heads”) are arrangedeach in a pair, in symmetrical placement with respect to reference axisLV. Z heads 72 a to 72 d are fixed to the lower surface of a main frame(not shown). Incidentally, Z heads 72 a to 72 d may also be arranged onthe measurement frame described above or the like.

As Z heads 72 a to 72 d, a sensor head that irradiates a light to wafertable WTB from above, receives the reflected light and measures positioninformation of the wafer table WTB surface in the Z-axis directionorthogonal to the XY plane at the irradiation point of the light, as anexample, a head of an optical displacement sensor (a sensor head by anoptical pickup method), which has a configuration like an optical pickupused in a CD drive device, is used.

Furthermore, head units 62A and 62C previously described arerespectively equipped with Z heads 76 _(j) and 74 _(i) (i, j=1-5), whichare five heads each, at the same X position as Y heads 65 _(j) and 64_(i) (i, j=1-5) that head units 62A and 62C are respectively equippedwith, with the Y position shifted In this case, Z heads 76 ₃ to 76 ₅ and74 ₁ to 74 ₃, which are three heads each on the outer side belonging tohead units 62A and 62C, respectively, are placed parallel to referenceaxis LH a predetermined distance away in the +Y direction from referenceaxis LH. Further, Z heads 76 ₁ and 74 ₅, which are heads on theinnermost side belonging to head units 62A and 62C, respectively, areplaced on the +Y side of projection unit PU, and Z heads 76 ₂ and 74 ₄,which are the second innermost heads are placed on the −Y side of Yheads 65 ₂ and 64 ₄, respectively. And Z heads 76 _(j), 74 _(i) (i,j=1-5), which are five heads each belonging to head unit 62A and 62 c,respectively, are placed symmetric to each other with respect toreference axis LV. Incidentally, as each of the Z heads 76 and 74, anoptical displacement sensor head similar to Z heads 72 a to 72 ddescribed above is employed. Incidentally, the configuration and thelike of the Z heads will be described later on.

In this case, Z head 74 ₃ is on a straight line parallel to the Y-axis,the same as is with Z heads 72 a and 72 b previously described.Similarly, Z head 76 ₃ is on a straight line parallel to the Y-axis, thesame as is with Z heads 72 c and 72 d previously described.

Further, the distance in a direction parallel to the Y-axis between Zhead 74 ₃ and Z head 74 ₄ and the distance in the direction parallel tothe Y-axis between Z head 76 ₃ and Z head 76 ₂ are approximately samewith a spacing in a direction parallel to the Y-axis between Z heads 72a and 72 b (coincides with the spacing in the direction parallel to theY-axis between Z heads 72 c and 72 d). Further, the distance in thedirection parallel to the Y-axis between Z head 74 ₃ and Z head 74 ₅ andthe distance in the direction parallel to the Y-axis between Z head 76 ₃and Z head 76 ₁ are slightly shorter than the spacing in a directionparallel to the Y-axis between Z heads 72 a and 72 b.

Z heads 72 a to 72 d, Z heads 74 ₁ to 74₅, and Z heads 76 ₁ to 76 ₅connect to main controller 20 via a signal processing/selection device170 as shown in FIG. 6, and main controller 20 selects an arbitrary Zhead from Z heads 72 a to 72 d, Z heads 74 ₁ to 74 ₅, and Z heads 76 ₁to 76 ₅ via signal processing/selection device 170 and makes the headmove into an operating state, and then receives the surface positioninformation detected by the Z head which is in an operating state viasignal processing/selection device 170. In the embodiment, a surfaceposition measurement system 180 (a part of measurement system 200) thatmeasures positional information of wafer stage WST in the Z-axisdirection and the direction of inclination with respect to the XY planeis configured, including Z heads 72 a to 72 d, z heads 74 ₁ to 74 ₅, andZ heads 76 ₁ to 76 ₅, and signal processing/selection device 170.

Incidentally, in FIG. 3, measurement stage MST is omitted and a liquidimmersion area that is formed by water Lq held in the space betweenmeasurement stage MST and tip lens 191 is shown by a reference code 14.Further, in FIG. 3, a reference code UP indicates an unloading positionwhere a wafer on wafer table WTB is unloaded, and a reference code LPindicates a loading position where a wafer is loaded on wafer table WTB.In the embodiment, unloading position UP and loading position LP are setsymmetrically with respect to straight line LV. Incidentally, unloadingposition UP and loading position LP may be the same position.

FIG. 6 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. In memory 34 which is anexternal memory connected to main controller 20, correction informationis stored of measurement instrument systems such as interferometersystem 118, encoder system 150 (encoders 70A to 70F), Z heads 72 a to 72d, 74 ₁ to 74 ₅, 76 ₁ to 76 ₅ and the like. Incidentally, in FIG. 6,various sensors such as irregular illuminance sensor 94, aerial imagemeasuring instrument 96 and wavefront aberration measuring instrument 98that are arranged at measurement stage MST are collectively shown as asensor group 99.

Next, the configuration and the like of Z heads 72 a to 72 d, 74 ₁ to 74₅, and 76 ₁ to 76 ₅ will be described, focusing on Z head 72 a shown inFIG. 7 as a representative.

As shown in FIG. 7, Z head 72 a is equipped with a focus sensor FS, asensor main section ZH which houses focus sensor FS, a drive section(not shown) which drives sensor main section ZH in the Z-axis direction,a measurement section ZE which measures displacement of sensor mainsection ZH in the Z-axis direction and the like.

As focus sensor FS, an optical displacement sensor similar to an opticalpickup used in a CD drive unit that irradiates a probe beam LB on ameasurement target surface S and optically reads the displacement ofmeasurement surface S by receiving the reflected light is used. Theconfiguration and the like of the focus sensor will be described laterin the description. The output signal of focus sensor FS is sent to thedrive section (not shown).

The drive section (not shown) includes an actuator such as, for example,a voice coil motor, and one of a mover and a stator of the voice coilmotor is fixed to sensor main section ZH, and the other is fixed to apart of a housing (not shown) which houses the sensor main section ZH,measurement section ZE and the like, respectively. The drive sectiondrives sensor main section ZH in the Z-axis direction according to theoutput signals from focus sensor FS so that the distance between sensormain section ZH and measurement target surface S is constantlymaintained (or to be more precise, so that measurement target surface Sis maintained at the best focus position of the optical system of focussensor FS). By this drive, sensor main section ZH follows thedisplacement of measurement target surface S in the Z-axis direction,and a focus lock state is maintained.

As measurement section ZE, in the embodiment, an encoder by thediffraction interference method is used as an example. Measurementsection ZE includes a reflective diffraction grating EG whose periodicdirection is the Z-axis direction arranged on a side surface of asupport member SM fixed on the upper surface of sensor main section ZHextending in the Z-axis direction, and an encoder head ER which isattached to the housing (not shown) facing diffraction grating EG.Encoder head EH reads the displacement of sensor main section ZH in theZ-axis direction by irradiating probe beam EL on diffraction grating EG,receiving the reflection/diffraction light from diffraction grating EGwith a light-receiving element, and reading the deviation of anirradiation point of probe beam EL from a reference point (for example,the origin).

In the embodiment, in the focus lock state, sensor main section ZH isdisplaced in the Z-axis direction so as to constantly maintain thedistance with measurement target surface S as described above.Accordingly, by encoder head EH of measurement section ZE measuring thedisplacement of sensor main section ZH in the Z-axis direction, surfaceposition (Z position) of measurement target surface S is measured.Measurement values of encoder head EH is supplied to main controller 20via signal processing/selection device 170 previously described asmeasurement values of Z head 72 a.

As shown in FIG. 8A, as an example, focus sensor FS includes threesections, an irradiation system FS₁, an optical system FS₂, and aphotodetection system FS₃.

Irradiation system FS1 includes, for example, a light source LD made upof laser diodes, and a diffraction grating plate (a diffractive opticalelement) ZG placed on the optical path of a laser beam outgoing fromlight source LD.

Optical system FS₂ includes, for instance, a diffraction light of thelaser beam generated in diffraction grating plate ZG, or morespecifically, a polarization beam splitter PUS, a collimator lens CL, aquarter-wave plate (a λ/4 plate) WP, and object lens OL and the likeplaced sequentially on the optical path of probe beam LB₁.

Photodetection system FS₃, for instance, includes a cylindrical lens CYLand a tetrameric light receiving element ZD placed sequentially on areturn optical path of reflected beam LB₂ of probe beam LB₁ onmeasurement target surface S.

According to focus sensor FS, the linearly polarized laser beamgenerated in light source LD of irradiation system FS1 is irradiated ondiffraction grating plate ZG, and diffraction light (probe beam) LB₁ isgenerated in diffraction grating plate ZG. The central axis (principalray) of probe beam LB₁ is parallel to the Z-axis and is also orthogonalto measurement target surface S.

Then, probe beam LB₁, or more specifically, light having a polarizationcomponent that is a P-polarized light with respect to a separation planeof polarization beam splitter PBS, is incident on optical system FS₂. Inoptical system FS₂, probe beam LB₁ passes through polarization beamsplitter PBS and is converted into a parallel beam at collimator lensCL, and then passes through λ/4 plate WP and becomes a circularpolarized light, which is condensed at object lens OL and is irradiatedon measurement target surface S. Accordingly, at measurement targetsurface S, reflected light (reflected beam) LB₂ occurs, which is acircular polarized light that proceeds inversely to the incoming lightof probe beam LB₁. Then, reflected beam LB₂ traces the optical path ofthe incoming light (probe beam LB₁) the other way around, and passesthrough object lens OL, λ/4 plate WP, collimator lens CL, and thenproceeds toward polarization beam splitter PBS. In this case, becausethe beam passes through λ/4 plate WP twice, reflected beam LB₂ isconverted into an S-polarized light. Therefore, the proceeding directionof reflected beam LB₂ is bent at the separation plane of polarizationbeam splitter PBS, so that it moves toward photodetection system FS₃.

In photodetection system FS₃, reflected beam LB₂ passes throughcylindrical lenses CYL and is irradiated on a detection surface oftetrameric light receiving element ZD. In this case, cylindrical lensesCYL is a “cambered type” lens, and as shown in FIG. 8B, the YZ sectionhas a convexed shape with the convexed section pointing the Y-axisdirection, and as shown also in FIG. 5C, the XY section has arectangular shape. Therefore, the sectional shape of reflected beam LB₂which passes through cylindrical lenses CYL is narrowed asymmetricallyin the Z-axis direction and the X-axis direction, which causesastigmatism.

Tetrameric light receiving element ZD receives reflected beam LB₂ on itsdetection surface. The detection surface of tetrameric light receivingelement ZD has a square shape as a whole, as shown in FIG. 9A, and it isdivided equally into four detection areas a, b, c, and d with the twodiagonal lines serving as a separation line. The center of the detectionsurface will be referred to as O_(ZD).

In this case, in an ideal focus state (a state in focus) shown in FIG.8A, or more specifically, in a state where probe beam LB₁ is focused onmeasurement target surface S₀, the cross-sectional shape of reflectedbeam LB₂ on the detection surface becomes a circle with center O_(ZD)serving as a center, as shown in FIG. 9C.

Further, in the so-called front-focused state (more specifically, astate equivalent to a state where measurement target surface S is atideal position S₀ and tetrameric light receiving element ZD is at aposition shown by reference code 1 in FIGS. 8B and 8C) where probe beamLB₁ focuses on measurement target surface S₁ in FIG. 8A, thecross-sectional shape of reflected beam LB₂ on the detection surfacebecomes a horizontally elongated circle with center OZD serving as acenter as shown in FIG. 9B.

Further, in the so-called back-focused state (more specifically, a stateequivalent to a state where measurement target surface S is at idealposition S₀ and tetrameric light receiving element ZD is at a positionshown by reference code-1 in FIGS. 8B and 8C) where probe beam LB₁focuses on measurement target surface S⁻¹ in FIG. 8A, thecross-sectional shape of reflected beam LB₂ on the detection surfacebecomes a longitudinally elongated circle with center O_(ZD) serving asa center as shown in FIG. 9D.

In an operational circuit (not shown) connected to tetrameric lightreceiving element ZD, a focus error I expressed as in the followingformula (7) is computed and output to the drive section (not shown),with the intensity of light received in the four detection areas a, b,c, and d expressed as Ia, Ib, Ic, and Id, respectively.I=(Ia+Ic)−(Ib+Id)  (7)

Incidentally, in the ideal focus state described above, because the areaof the beam cross-section in each of the four detection areas is equalto each other, focus error I=0 can be obtained. Further, in the frontfocused state described above, according to formula (7), focus errorbecomes I<0, and in the back focused state, according to formula (7),focus error becomes I>0.

The drive section (not shown) receives focus error I from a detectionsection FS3 within focus sensor FS, and drives sensor main body ZH whichstored focus sensor FS in the Z-axis direction so as to reproduce I=0.By this operation of the drive section, because sensor main section ZHis also displaced following measurement target surface S, the probe beamfocuses on measurement target surface S without fail, or morespecifically, the distance between sensor main section ZH andmeasurement target surface S is always constantly maintained (focus lockstate is maintained).

Meanwhile, the drive section (not shown) can also drive and positionsensor main section ZH in the Z-axis direction so that a measurementresult of measurement section ZE coincides with an input signal from theoutside of Z head 72 a. Accordingly, the focus of probe beam LB can alsobe positioned at a position different from the actual surface positionof measurement target surface S. By this operation (scale servo control)of the drive section, processes such as return process in the switchingof the Z heads, avoidance process at the time of abnormality generationin the output signals and the like can be performed.

In the embodiment, as is previously described, an encoder is adopted asmeasuring section ZE, and encoder head EH is used to read the Zdisplacement of diffraction grating EG set in sensor main section ZH.Because encoder head EH is a relative position sensor which measures thedisplacement of the measurement object (diffraction grating EG) from areference point, it is necessary to determine the reference point. Inthe embodiment, the reference position (for example, the origin) of theZ displacement can be determined by detecting an edge section ofdiffraction grating EG, or in the case a lay out pattern is arranged indiffraction grating EG, by detecting the lay out pattern. In any case,reference surface position of measurement target surface S can bedetermined in correspondence with the reference position of diffractiongrating EG, and the Z displacement of measurement target surface S fromthe reference surface position, or more specifically, the position inthe Z-axis direction can be measured. Incidentally, at the start up andthe restoration of the Z head, setting of the reference position (forexample, the origin, or more specifically, the reference surfaceposition of measurement target surface S) of diffraction grating EG isexecuted without fail. In this case, it is desirable for the referenceposition to be set around the center of the movement range of sensormain section ZH. Therefore, a drive coil for adjusting the focalposition of the optical system can be arranged to adjust the Z positionof object lens OL so that the reference surface position correspondingto the reference position around the center coincides with the focalposition of the optical system in the focus sensor FS. Further, whensensor main section ZH is located at the reference position (forexample, the origin), measurement section ZE is made to generate anorigin detection signal.

In Z head 72 a, because sensor main section ZH and measurement sectionZE are housed together inside the housing (not shown) and the part ofthe optical path length of probe beam LB₁ which is exposed outside thehousing is extremely short, the influence of air fluctuation isextremely small. Accordingly, even when compared, for example, with alaser interferometer, the sensor including the Z head is much moresuperior in measurement stability (short-term stability) during a periodas short as while the air fluctuates.

The other Z heads are also configured and function in a similar manneras Z head 72 a described above. As is described, in the embodiment, aseach Z head, a configuration is employed where the diffraction gratingsurfaces of Y scales 39Y₁, 39Y₂ and the like are observed from above(the +Z direction) as in the encoder. Accordingly, by measuring thesurface position information of the upper surface of wafer table WTB atdifferent positions with the plurality of Z heads, the position of waferstage WST in the Z-axis direction, the θy rotation (rolling), and the θxrotation (pitching) can be measured. However, in the embodiment, in viewof the configuration where one Z head each faces Y scales 39Y₁ and 39Y₂on exposure, the surface position measurement system including the Zhead does not measure pitching.

Next, detection of position information (surface position information)of the wafer W surface in the Z-axis direction (hereinafter, referred toas focus mapping) that is performed in exposure apparatus 100 of theembodiment will be described.

On the focus mapping, as is shown in FIG. 10A, main controller 20controls the position within the XY plane of wafer stage WST based on Xhead 66 ₃ facing X scale 39X₂ (X linear encoder 70D) and two Y heads 68₂ and 67 ₃ facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70F₁ and 70E₁). In the state of FIG. 10A, a straight line (centerline)parallel to the Y-axis that passes through the center of wafer table WTB(which substantially coincides with the center of wafer W) coincideswith reference line LV previously described. Further, although it isomitted in the drawing here, measurement stage MST is located on the +Yside of wafer stage WST, and water is retained in the space between FDbar 46, wafer table WTB and tip lens 191 of projection optical system PLpreviously described (refer to FIG. 18).

Then, in this state, main controller 20 starts scanning of wafer stageWST in the +Y direction, and after having started the scanning,activates (turns ON) both Z heads 72 a to 72 d and the multipoint AFsystem (90 a, 90 b) by the time when wafer stage WST moves in the +Ydirection and detection beams (detection area AF) of the multipoint AFsystem (90 a, 90 b) begin to be irradiated on wafer W.

Then, in a state where Z heads 72 a to 72 d and the multipoint AF system(90 a, 90 b) simultaneously operate, as is shown in FIG. 10B, positioninformation (surface position information) of the wafer table WTBsurface (surface of plate 28) in the Z-axis direction that is measuredby Z heads 72 a to 72 d and position information (surface positioninformation) of the wafer W surface in the Z-axis direction at aplurality of detection points that is detected by the multipoint AFsystem (90 a, 90 b) are loaded at a predetermined sampling intervalwhile wafer stage WST is proceeding in the +Y direction, and three kindsof information, which are the two kinds of surface position informationthat has been loaded and the measurement values of Y linear encoders70F₁ and 70E₁ at the time of each sampling, are made to correspond toone another, and then are sequentially stored in memory (not shown).

Then, when the detection beams of the multipoint AF system (90 a, 90 b)begin to miss wafer W, main controller 20 ends the sampling describedabove and converts the surface position information at each detectionpoint of the multipoint AF system (90 a, 90 b) into data which uses thesurface position information by Z heads 72 a to 72 d that has beenloaded simultaneously as a reference.

More specifically, based on an average value of the measurement valuesof Z heads 72 a and 72 b, surface position information at apredetermined point (for example, corresponding to a midpoint of therespective measurement points of Z heads 72 a and 72 b, that is, a pointon substantially the same X-axis as the array of a plurality ofdetection points of the multipoint AF system (90 a, 90 b): hereinafter,this point is referred to as a left measurement point P1) on an area (anarea where Y scale 39Y₂ is formed) near the edge section on the −X sideof plate 28 is obtained. Further, based on an average value of themeasurement values of Z heads 72 c and 72 d, surface positioninformation at a predetermined point (for example, corresponding to amidpoint of the respective measurement points of Z heads 72 c and 72 d,that is, a point on substantially the same X-axis as the array of aplurality of detection points of the multipoint AF system (90 a, 90 b):hereinafter, this point is referred to as a right measurement point P2)on an area (an area where Y scale 39Y₁ is formed) near the edge sectionon the +X side of plate 28 is obtained. Then, as shown in FIG. 10C, maincontroller 20 converts the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) into surfaceposition data z1-zk, which uses a straight line that connects thesurface position of left measurement point P1 and the surface positionof right measurement point P2 as a reference. Main controller 20performs such a conversion on all information taken in during thesampling.

By obtaining such converted data in advance in the manner describedabove, for example, in the case of exposure, main controller 20 measuresthe wafer table WTB surface (a point on the area where Y scale 39Y₂ isformed (a point near left measurement point P1 described above) and apoint on the area where Y scale 39Y₃ is formed (a point near rightmeasurement point P1 described above)) with Z heads 74 _(i) and 76 _(j)previously described, and computes the Z position and θy rotation(rolling) amount θy of wafer stage WST. Then, by performing apredetermined operation using the Z position, the rolling amount θy, andthe θx rotation (pitching) amount θx of wafer stage WST measured with Yinterferometer 16, and computing the Z position (Z₀), rolling amount θy,and pitching amount θx of the wafer table WTB surface in the center (theexposure center) of exposure area IA previously described, and thenobtaining the straight line passing through the exposure center thatconnects the surface position of left measurement point P1 and thesurface position of right measurement point P2 described above based onthe computation results, it becomes possible to perform the surfaceposition control (focus leveling control) of the upper surface of waferW without actually acquiring the surface position information of thewafer W surface by using such straight line and surface position dataz1-zk. Accordingly, because there is no problem even if the multipointAF system is placed at a position away from projection optical systemPL, the focus mapping of the embodiment can suitably be applied also toan exposure apparatus and the like that has a short working distance.

Incidentally, in the description above, while the surface position ofleft measurement point P1 and the surface position of right measurementpoint P2 were computed based on the average value of the measurementvalues of Z heads 72 a and 72 b, and the average value of Z heads 72 cand 72 d, respectively, the surface position information at eachdetection point of the multipoint AF system (90 a, 90 b) can also beconverted, for example, into surface position data which uses thestraight line connecting the surface positions measured by Z heads 72 aand 72 c as a reference. In this case, the difference between themeasurement value of Z head 72 a and the measurement value of Z head 72b obtained at each sampling timing, and the difference between themeasurement value of Z head 72 c and the measurement value of Z head 72d obtained at each sampling timing are to be obtained severally inadvance. Then, when performing surface position control at the time ofexposure or the like, by measuring the wafer table WTB surface with Zheads 74 _(i) and 76 _(j) and computing the z-position and the θyrotation of wafer stage WST, and then performing a predeterminedoperation using these computed values, pitching amount θx of wafer stageWST measured by Y interferometer 16, surface position data z1 to zkpreviously described, and the differences described above, it becomespossible to perform surface position control of wafer W, withoutactually obtaining the surface position information of the wafersurface.

However, the description so far is made, assuming that unevenness doesnot exist on the wafer table WTB surface in the X-axis direction. In thedescription below, unevenness will not exist on the wafer table WTBsurface in the X-axis direction.

Next, focus calibration will be described. Focus calibration refers to aprocess where a processing of obtaining a relation between surfaceposition information of wafer table WTB at end portions on one side andthe other side in the X-axis direction in a reference state anddetection results (surface position information) at representativedetection points on the measurement plate 30 surface of multipoint AFsystem (90 a, 90 b) (former processing of focus calibration), and aprocessing of obtaining surface position information of wafer table WTBat end portions on one side and the other side in the X-axis directionthat correspond to the best focus position of projection optical systemPL detected using aerial image measurement device 45 in a state similarto the reference state above (latter processing of focus calibration)are performed, and based on these processing results, an offset ofmultipoint AF system (90 a, 90 b) at representative detection points, orin other words, a deviation between the best focus position ofprojection optical system PL and the detection origin of the multipointAF system, is obtained.

On the focus calibration, as is shown in FIG. 11A, main controller 20controls the position within the XY plane of wafer stage WST based on Xhead 66 ₂ facing X scale 39X₂ (X linear encoder 70D) and two Y heads 68₂ and 67 ₃ facing Y scales 39Y₁ and 39Y₂ respectively (Y linear encoders70F₁ and 70E₁). The state of FIG. 11A is substantially the same as thestate in 10A previously described. However, in the state of FIG. 11A,wafer stage WST is at a position where a detection beam from multipointAF system (90 a, 90 b) is irradiated on measurement plate 30 previouslydescribed in the Y-axis direction.

(a) In this state, main controller 20 performs the former processing offocus calibration as in the following description. More specifically,while detecting surface position information of the end portions on oneside and the other side of wafer table WTB in the X-axis direction thatis detected by Z heads 72 a, 72 b, 72 c and 72 d previously described,main controller 20 uses the surface position information as a reference,and detects surface position information of the measurement plate 30(refer to FIG. 3) surface previously described using the multipoint AFsystem (90 a, 90 b). Thus, a relation between the measurement values ofZ heads 72 a, 72 b, 72 c and 72 d (surface position information at endportions on one side and the other side of wafer table WTB in the X-axisdirection) and the detection results (surface position information) at adetection point (the detection point located in the center or thevicinity thereof out of a plurality of detection points) on themeasurement plate 30 surface of the multipoint AF system (90 a, 90 b),in a state where the centerline of wafer table WTB coincides withreference line LV, is obtained.(b) Next, main controller 20 moves wafer stage WST in the +Y directionby a predetermined distance, and stops wafer stage WST at a positionwhere measurement plate 30 is located directly below projection opticalsystem PL. Then, main controller 20 performs the latter processing offocus calibration as follows. More specifically, as is shown in FIG.11B, while controlling the position of measurement plate 30 (wafer stageWST) in the optical axis direction of projection optical system PL (theZ position), using surface position information measured by Z heads 72a, 72 b, 72 c, and 72 d as a reference as in the former processing offocus calibration, main controller 20 measures an aerial image of ameasurement mark formed on reticle R or on a mark plate (not shown) onreticle stage RST by a Z direction scanning measurement whose detailsare disclosed in, for example, the pamphlet of International PublicationNo. 2005/124834 and the like, using aerial image measurement device 45,and based on the measurement results, measures the best focus positionof projection optical system PL. During the Z direction scanningmeasurement described above, main controller 20 takes in measurementvalues of a pair of Z heads 74 ₃ and 76 ₃ which measure the surfaceposition information at end portions on one side and the other side ofwafer table WTB in the X-axis direction, in synchronization with takingin output signals from aerial image measurement device 45. Then, maincontroller 20 stores the values of Z heads 74 ₃ and 76 ₃ correspondingto the best focus position of projection optical system PL in memory(not shown). Incidentally, the reason why the position (Z position)related to the optical axis direction of projection optical system PL ofmeasurement plate 30 (wafer stage WST) is controlled using the surfaceposition information measured in the latter processing of the focuscalibration by Z heads 72 a, 72 b, 72 c, and 72 d is because the latterprocessing of the focus calibration is performed during the focusmapping previously described.

In this case, because liquid immersion area 14 is formed betweenprojection optical system PL and measurement plate 30 (wafer table WTB)as shown in FIG. 11B, the measurement of the aerial image is performedvia projection optical system PL and the water. Further, although it isomitted in FIG. 11B, because measurement plate 30 and the like of aerialimage measurement device 45 are installed in wafer stage WST, and thelight receiving elements are installed in measurement stage MST, themeasurement of the aerial image described above is performed while waferstage WST and measurement stage MST maintain a contact state (or aproximity state) (refer to FIG. 20).

(c) Accordingly, main controller 20 can obtain the offset at therepresentative detection point of the multipoint AF system (90 a, 90 b),or more specifically, the deviation between the best focus position ofprojection optical system PL and the detection origin of the multipointAF system, based on the relation between the measurement values of Zheads 72 a, 72 b, 72 c, and 72 d (surface position information at theend portions on one side and the other side in the X axis direction ofwafer table WTB) and the detection results (surface positioninformation) of the measurement plate 30 surface by the multipoint AFsystem (90 a, 90 b) obtained in (a) described above, in the formerprocessing of focus calibration, and also on the measurement values of Zheads 74 ₃ and 76 ₃ (that is, surface position information at the endportions on one side and the other side in the X-axis direction of wafertable WTB) corresponding to the best focus position of projectionoptical system PL obtained in (b) described above, in the latterprocessing of focus calibration. In the embodiment, the representativedetection point is, for example, the detection point in the center ofthe plurality of detection points or in the vicinity thereof, but thenumber and/or the position may be arbitrary. In this case, maincontroller 20 adjusts the detection origin of the multipoint AF systemso that the offset at the representative detection point becomes zero.The adjustment may be performed, for example, optically, by performingangle adjustment of a plane parallel plate (not shown) insidephotodetection system 90 b, or the detection offset may be electricallyadjusted. Alternatively, the offset may be stored, without performingadjustment of the detection origin. In this case, adjustment of thedetection origin is to be performed by the optical method referred toabove. This completes the focus calibration of the multipoint AF system(90 a, 90 b). Incidentally, because it is difficult to make the offsetbecome zero at all the remaining detection points other than therepresentative detection point by adjusting the detection originoptically, it is desirable to store the offset after the opticaladjustment at the remaining detection points.

Next, offset correction of detection values among a plurality oflight-receiving elements (sensors) that individually correspond to aplurality of detection points of the multiple AF system (90 a, 90 b)(hereinafter, referred to as offset correction among AF sensors) will bedescribed.

On the offset correction among AF sensors, as is shown in FIG. 12A, maincontroller 20 makes irradiation system 90 a of the multipoint AF system(90 a, 90 b) irradiate detection beams to FD bar 46 equipped with apredetermined reference plane, and takes in output signals fromphotodetection system 90 b of the multipoint AF system (90 a, 90 b) thatreceives the reflected lights from the FD bar 46 surface (referenceplane).

In this case, if the FD bar 46 surface is set parallel to the XY plane,main controller 20 can perform the offset correction among AF sensors byobtaining a relation among the detection values (measurement values) ofa plurality of sensors that individually correspond to a plurality ofdetection points based on the output signals loaded in the mannerdescribed above and storing the relation in a memory, or by electricallyadjusting the detection offset of each sensor so that the detectionvalues of all the sensors become, for example, the same value as thedetection value of a sensor that corresponds to the representativedetection point on the focus calibration described above.

In the embodiment, however, as is shown in FIG. 12A, because maincontroller 20 detects the inclination of the surface of measurementstage MST (integral with FD bar 46) using Z heads 74 ₄, 74 ₅, 76 ₁, and76 ₂ when taking in the output signals from photodetection system 90 bof the Multipoint AF system (90 a, 90 b), the FD bar 46 surface does notnecessarily have to be set parallel to the XY plane. In other words, asis modeled in FIG. 12B, when it is assumed that the detection value ateach detection point is the value as severally indicated by arrows inthe drawing, and the line that connects the upper end of the detectionvalues has an unevenness as shown in the dotted line in the drawing,each detection value only has to be adjusted so that the line thatconnects the upper end of the detection values becomes the solid lineshown in the drawing.

Next, a parallel processing operation that uses wafer stage WST andmeasurement stage MST in exposure apparatus 100 of the embodiment willbe described based on FIGS. 13 to 23. Incidentally, during the operationbelow, main controller 20 performs the open/close control of each valveof liquid supply unit 5 of local liquid immersion unit 8 and liquidrecovery unit 6 in the manner previously described, and water isconstantly filled on the outgoing surface side of tip lens 191 ofprojection optical system PL. However, in the description below, for thesake of simplicity, the explanation related to the control of liquidsupply unit 5 and liquid recovery unit 6 will be omitted. Further, manydrawings are used in the operation description hereinafter, however,reference codes may or may not be given to the same member for eachdrawing. More specifically, the reference codes written are differentfor each drawing; however, such members have the same configuration,regardless of the indication of the reference codes. The same can besaid for each drawing used in the description so far.

FIG. 13 shows a state in which an exposure by the step-and-scan methodof wafer W mounted on wafer stage WST is performed. This exposure isperformed by repeating a movement between shots in which wafer stage WSTis moved to a scanning starting position (acceleration staring position)to expose each shot area on wafer W and scanning exposure in which thepattern formed on reticle R is transferred onto each shot area by thescanning exposure method, based on results of wafer alignment (EGA:Enhanced Global Alignment) and the like which has been performed priorto the beginning of exposure. Further, exposure is performed in thefollowing order, from the shot area located on the −Y side on wafer W tothe shot area located on the +Y side. Incidentally, exposure isperformed in a state where liquid immersion area 14 is formed in betweenprojection unit PU and wafer W.

During the exposure described above, the position (including rotation inthe θz direction) of wafer stage WST in the XY plane is controlled bymain controller 20, based on measurement results of a total of threeencoders which are the two Y encoders 70A and 70 c, and one of the two Xencoders 70B and 70D. In this case, the two X encoders 70B and 70D aremade up of two X heads 66 that face X scale 39X₁ and 39X₂, respectively,and the two Y encoders 70A and 70C are made up of Y heads 65 and 64 thatface Y scales 39Y₁ and 39Y₂, respectively. Further, the Z position androtation (rolling) in the θy direction of wafer stage WST arecontrolled, based on measurement results of Z heads 74 _(i) and 76 _(j),which respectively belong to head units 62C and 62A facing the endsection on one side and the other side of the surface of wafer table WTBin the X-axis direction, respectively. The θx rotation (pitching) ofwafer stage WST is controlled based on measurement values of Yinterferometer 16. Incidentally, in the case three or more Z headsincluding Z head 74 _(i) and 76 _(i) face the surface of the secondwater repellent plate 28 b of wafer table WTB, it is also possible tocontrol the position of wafer stage WST in the Z-axis direction, the θyrotation (rolling), and the θx rotation (pitching), based on themeasurement values of Z heads 74 _(i), 76 _(i) and the other one head.In any case, the control (more specifically, the focus leveling controlof wafer W) of the position of wafer stage WST in the Z-axis direction,the rotation in the θy direction, and the rotation in the θx directionis performed, based on results of a focus mapping performed beforehand.

At the position of wafer stage WST shown in FIG. 13, while X head 66 ₅(shown circled in FIG. 13) faces X scale 39X₁, there are no X heads 66that face X scale 39X₂. Therefore, main controller 20 uses one X encoder70B and two Y encoders 70A and 70C so as to perform position (X, Y, θz)control of wafer stage WST. In this case, when wafer stage WST movesfrom the position shown in FIG. 13 to the −Y direction, X head 66 ₅moves off of (no longer faces) X scale 39X₁, and X head 66 ₄ (showncircled in a broken line in FIG. 13) faces X scale 39X₂ instead.Therefore, main controller 20 switches the control to a position (X, Y,θz) control of wafer stage WST that uses one X encoder 70D and two Yencoders 70A and 70C.

Further, when wafer stage WST is located at the position shown in FIG.13, Z heads 74 ₃ and 76 ₃ (shown circled in FIG. 13) face Y scales 39Y₂and 39Y₁, respectively. Therefore, main controller 20 performs position(Z, θy) control of wafer stage WST using Z heads 74 ₃ and 76 ₃. In thiscase, when wafer stage WST moves from the position shown in FIG. 13 tothe +X direction, Z heads 74 ₃ and 76 ₃ move off of (no longer faces)the corresponding Y scales, and Z heads 74 ₄ and 76 ₄ (shown circled ina broken line in FIG. 13) respectively face Y scales 39Y₂ and 39Y₁instead. Therefore, main controller 20 switches to a stage control usingZ heads 74 ₄ and 76 ₄.

In this manner, main controller 20 performs position control of waferstage WST by consistently switching the encoder to use depending on theposition coordinate of wafer stage WST.

Incidentally, independent from the position measurement of wafer stageWST described above using the measuring instrument system describedabove, position (X, Y, Z, θx, θy, θz) measurement of wafer stage WSTusing interferometer system 118 is constantly performed. In this case,the X position and θz rotation (yawing) of wafer stage WST or the Xposition are measured using X interferometers 126, 127, or 128, the Yposition, the θx rotation, and the θz rotation are measured using Yinterferometer 16, and the Y position, the Z position, the θy rotation,and the θz rotation are measured using Z interferometers 43A and 43B(not shown in FIG. 13, refer to FIG. 1 or 2) that constituteinterferometer system 118. Of X interferometers 126, 127, and 128, oneinterferometer is used according to the Y position of wafer stage WST.As indicated in FIG. 13, X interferometer 126 is used during exposure.The measurement results of interferometer system 118 except for pitching(θx rotation) are used for position control of wafer stage WSTsecondarily, or in the case of backup which will be described later on,or when measurement using encoder system 150 cannot be performed.

When exposure of wafer W has been completed, main controller 20 driveswafer stage WST toward unloading position UP. On this drive, wafer stageWST and measurement stage MST which were apart during exposure come intocontact or move close to each other with a clearance of around 300 μm inbetween, and shift to a scrum state. In this case, the −Y side surfaceof FD bar 46 on measurement table MTB and the +Y side surface of wafertable WTB come into contact or move close together. And by moving bothstages WST and MST in the −Y direction while maintaining the scrumcondition, liquid immersion area 14 formed under projection unit PUmoves to an area above measurement stage MST. For example, FIGS. 14 and15 show the state after the movement.

When wafer stage WST moves further to the −Y direction and moves offfrom the effective stroke area (the area in which wafer stage WST movesat the time of exposure and wafer alignment) after the drive of waferstage WST toward unloading position UP has been started, all the X headsand Y heads, and all the Z heads that constitute encoder 70A to 70D moveoff from the corresponding scale on wafer table WTB. Therefore, positioncontrol of wafer stage WST based on the measurement results of encoders70A to 70D and the Z heads is no longer possible. Just before this, maincontroller 20 switches the control to a position control of wafer stageWST based on the measurement results of interferometer system 118. Inthis case, of the three X interferometers 126, 127, and 128, Xinterferometer 128 is used.

Then, wafer stage WST releases the scrum state with measurement stageMST, and then moves to unloading position UP as shown in FIG. 14. Afterthe movement, main controller 20 unloads wafer W on wafer table WTB. Andthen, main controller 20 drives wafer stage WST in the +X direction toloading position LP, and the next wafer W is loaded on wafer table WTBas shown in FIG. 15.

In parallel with these operations, main controller 20 performs Sec-BCHK(a secondary base line check) in which position adjustment of FD bar 46supported by measurement stage MST in the XY plane and baselinemeasurement of the four secondary alignment system AL2 ₁ to AL2 ₄ areperformed. Sec-BCHK is performed on an interval basis for every waferexchange. In this case, in order to measure the position (the θzrotation) in the XY plane, Y encoders 70E₂ and 70F₂ previously describedare used.

Next, as shown in FIG. 16, main controller 20 drives wafer stage WST andpositions reference mark FM on measurement plate 30 within a detectionfield of primary alignment system AL1, and performs the former processof Pri-BCHK (a primary baseline check) in which the reference positionis decided for baseline measurement of alignment system AL1, and AL2 ₁to AL2 ₄.

On this process, as shown in FIG. 16, two Y heads 68 ₂ and 67 ₃ and oneX head 66 (shown circled in the drawing) come to face Y scales 39Y₁ and39Y₂, and X scale 39X₂, respectively. Then, main controller 20 switchesthe stage control from a control using interferometer system 118, to acontrol using encoder system 150 (encoders 70F₁, 70E₁, and 70D).Interferometer system 118 is used secondarily again, except inmeasurement of the θx rotation. Incidentally, of the three Xinterferometers 126, 127, and 128, X interferometer 127 is used.

Next, while controlling the position of wafer stage WST based on themeasurement values of the three encoders described above, maincontroller 20 begins the movement of wafer stage WST in the +Y directiontoward a position where an alignment mark arranged in three firstalignment shot areas is detected.

Then, when wafer stage WST reaches the position shown in FIG. 17, maincontroller 20 stops wafer stage WST. Prior to this operation, maincontroller 20 activates (turns ON) Z heads 72 a to 72 d and startsmeasurement of the Z-position and the tilt (the θy rotation) of wafertable WTB at the point in time when all of or part of Z heads 72 a to 72d face(s) wafer table WTB, or before that point in time.

After wafer stage WST is stopped, main controller 20 detects thealignment mark arranged in the three first alignment shot areassubstantially at the same time and also individually (refer to thestar-shaped marks in FIG. 17), using primary alignment system AL1, andsecondary alignment systems AL2 ₂ and AL2 ₃, and makes a link betweenthe detection results of the three alignment systems AL1, AL2 ₂, and AL2₃ and the measurement values of the three encoders above at the time ofthe detection, and stores them in memory (not shown).

As in the description above, in the embodiment, the shift to the contactstate (or proximity state) between measurement stage MST and wafer stageWST is completed at the position where detection of the alignment marksof the first alignment shot area is performed. And from this position,main controller 20 begins to move both stages WST and MST in the +Ydirection (step movement toward the position for detecting an alignmentmark arranged in five second alignment shot areas) in the contact state(or proximity state). Prior to starting the movement of both stages WSTand MST in the +Y direction, as shown in FIG. 17, main controller 20begins irradiation of a detection beam from irradiation system 90 of themultipoint AF system (90 a, 90 b) to wafer table WTB. Accordingly, adetection area of the multipoint AF system is formed on wafer table WTB.

Then, when both stages WST and MST reach the position shown in FIG. 18during the movement of both stages WST and MST in the +Y direction, maincontroller 20 performs the former process of the focus calibration, andobtains the relation between the measurement values (surface positioninformation on one side and the other side of wafer table WTB in theX-axis direction) of Z heads 72 a, 72 b, 72 c, and 72 d, in a statewhere the center line of wafer table WTB coincides with reference axisLV, and the detection results (surface position information) of thesurface of measurement plate 30 by the multipoint AF system (90 a, 90b). At this point, liquid immersion area 14 is formed on the uppersurface of FD bar 46.

Then, both stages WST and MST move further in the +Y direction whilemaintaining the contact state (or proximity state), and reach theposition shown in FIG. 19. Then, main controller 20 detects thealignment mark arranged in the five second alignment shot areassubstantially at the same time as well as individually (refer to thestar-shaped marks in FIG. 19), using the five alignment systems AL1, andAL2 ₁ to AL2 ₄, and makes a link between the detection results of thefive alignment systems AL1, and AL2 ₁ to AL2 ₄ and the measurementvalues of the three encoders measuring the position of wafer stage WSTin the XY plane at the time of the detection, and then stores them inmemory (not shown). At this point, main controller 20 controls theposition of wafer stage WST within the XY plane based on the measurementvalues of X head 66 ₂ (X linear encoder 70D) that faces X scale 39X₂ andY linear encoders 70F₁ and 70E₁.

Further, after the simultaneous detection of the alignment marksarranged in the five second alignment shot areas ends, main controller20 starts again movement in the +Y direction of both stages WST and MSTin the contact state (or proximity state), and at the same time, startsthe focus mapping previously described using Z heads 72 a to 72 d andthe multipoint AF system (90 a, 90 b), as is shown in FIG. 19.

Then, when both stages WST and MST reach the position shown in FIG. 20where measurement plate 30 is located directly below projection opticalsystem PL, main controller 20 performs the latter processing of focuscalibration in a state while continuing to control the Z position ofwafer stage WST (measurement plate 30) that uses the surface positioninformation measured by Z heads 72 a, 72 b, 72 c, and 72 d as areference, without switching the Z head used for position (Z position)control of wafer stage WST in the optical axis direction of projectionoptical system PL to Z heads 74 _(i) and 76 _(j).

Then, main controller 20 obtains the offset at the representativedetection point of the multipoint AF system (90 a, 90 b) based on theresults of the former processing and latter processing of focuscalibration described above, and adjusts the detection origin of themultipoint AF system by the optical method previously described so thatthe offset at the representative detection point becomes zero.

Incidentally, in the state of FIG. 20, the focus mapping is beingcontinued.

When wafer stage WST reaches the position shown in FIG. 21 by movementin the +Y direction of both stages WST and MST in the contact state (orproximity state) described above, main controller 20 stops wafer stageWST at that position, while making measurement stage MST continue themovement in the +Y direction. Then, main controller 20 detects thealignment mark arranged in the five second alignment shot areassubstantially at the same time as well as individually (refer to thestar-shaped marks in FIG. 21), using the five alignment systems AL1, andAL2 ₁ to AL2 ₄, and makes a link between the detection results of thefive alignment systems AL1, and AL2 ₁ to AL2 ₄ and the measurementvalues of the three encoders at the time of the detection, and thenstores them in the internal memory. Further, at this point as well, thefocus mapping is being continued.

Meanwhile, after a predetermined period of time from the suspension ofwafer stage WST described above, measurement stage MST and wafer stageWST move from the contact state (or proximity state) into a separationstate. After the shift to the separation state, main controller 20 stopsthe movement of measurement stage MST when measurement stage MST reachesan exposure start waiting position where measurement stage MST waitsuntil exposure is started.

Next, main controller 20 starts the movement of wafer stage WST in the+Y direction toward a position where the alignment mark arranged in thethree fourth alignment shots are detected. At this point in time, thefocus mapping is being continued. Meanwhile, measurement stage MST iswaiting at the exposure start waiting position described above.

Then, when wafer stage WST reaches the position shown in FIG. 22, maincontroller 20 immediately stops wafer stage WST, and almostsimultaneously and individually detects the alignment marks arranged inthe three fourth alignment shot areas on wafer W (refer to star-shapedmarks in FIG. 22) using primary alignment system AL1 and secondaryalignment systems AL2 ₂ and AL2 ₃, links the detection results of threealignment systems AL1, AL2 ₂ and AL2 ₃ and the measurement values of thethree encoders out of the four encoders above at the time of thedetection, and stores them in memory (not shown). Also at this point intime, the focus mapping is being continued, and measurement stage MST isstill waiting at the exposure start waiting position. Then, using thedetection results of a total of 16 alignment marks and the measurementvalues of the corresponding encoders obtained in the manner describedabove, main controller 20 computes array information (coordinate values)of all the shot areas on wafer W on an alignment coordinate system (anXY coordinate system whose origin is placed at the detection center ofprimary alignment system AL1) that is set by the measurement axes ofencoders 70B, 70D, 70E₁, and 70F₁ of encoder system 150, by performing astatistical computation disclosed in, for example, U.S. Pat. No.4,780,617 and the like.

Next, main controller 20 continues the focus mapping while moving waferstage WST in the +Y direction again. Then, when the detection beam fromthe multipoint AF system (90 a, 90 b) begins to miss the wafer Wsurface, as is shown in FIG. 23, main controller 20 ends the focusmapping.

After the focus mapping has been completed, main controller 20 moveswafer stage WST to a scanning starting position (exposure startingposition) for exposure of the first shot on wafer W, and during themovement, main controller 20 switches the Z heads used for control ofthe Z position and the θy rotation of wafer stage WST from Z heads 72 ato 72 d to Z heads 74 _(i) and 74 _(j) while maintaining the Z position,the θy rotation, and the θx rotation of wafer stage WST. After thisswitching, based on the results of the wafer alignment (EGA) previouslydescribed and the latest baselines and the like of the five alignmentsystems AL1 and AL2 ₁ to AL2 ₄, main controller 20 performs exposure bya step-and-scan method in a liquid immersion exposure, and sequentiallytransfers a reticle pattern to a plurality of shot areas on wafer W.Hereinafter, a similar operation is performed repeatedly.

Next, a computation method of the Z position and the amount of tilt ofwafer stage WST using the measurement results of the Z heads will bedescribed. Main controller 20 uses the four Z heads 70 a to 70 d thatconstitute surface position measurement system 180 (refer to FIG. 6) atthe time of focus calibration and focus mapping, and measures height Zand tilt (rolling) θy of wafer stage WST. Further, main controller 20uses two Z heads 74 _(i) and 76 _(j) (i and j are one of 1 to 5) at thetime of exposure, and measures height Z of wafer stage WST and tilt(rolling) θy. Incidentally, each Z head irradiates a probe beam on theupper surface (a surface of a reflection grating formed on the uppersurface) of the corresponding Y scales 39Y₁ or 39Y₂, and measures thesurface position of the reflection grating by receiving the reflectedlight.

FIG. 24A shows a two-dimensional plane having height Z₀, rotation angle(an angle of inclination) around the X-axis θx, and rotation angle (anangle of inclination) around the Y-axis θy at a reference point O.Height Z at position (X, Y) of this plane is given by a functionaccording to the next formula (8).f(X,Y)=−tan θy·X+tan θx·Y+Z ₀  (8)

As shown in FIG. 24B, at the time of the exposure, height Z from amovement reference surface (a surface that is substantially parallel tothe XY plane) of wafer table WTB and rolling θy are measured at anintersection point (reference point) O of a movement reference surfaceof wafer stage WST and optical axis AX of projection optical system PL,using two Z heads 74 _(i) and 76 _(j) (i and j are one of 1 to 5). Inthis case, Z heads 74 ₃ and 76 ₃ are used as an example. Similar to theexample shown in FIG. 24A, the height of wafer table WTB at referencepoint O will be expressed as Z₀, the tilt (pitching) around the X-axiswill be expressed as θx, and the tilt (rolling) around the Y-axis willbe expressed as θy. In this case, measurement values Z_(L) and Z_(R) ofthe surface position of (reflection gratings formed on) Y scales 39Y₁and 39Y₂ indicated by Z head 74 ₃, which is located at coordinate(p_(L), q_(L)), and Z head 76 ₃, which is located at coordinate (p_(R),q_(R)) in the XY plane, respectively, follow theoretical formulas (9)and (10), similar to formula (8).Z _(L)=−tan θy·p _(L)+tan θx·q _(L) +Z ₀  (9)Z _(R)=−tan θy·p _(R)+tan θx·q _(R) +Z ₀  (10)

Accordingly, from theoretical formulas (9) and (10), height Z₀ of wafertable WTB and rolling θy at reference point O can be expressed as in thefollowing formulas (11) and (12) using measurement values Z_(L) andZ_(R) of Z heads 74 ₃ and 76 ₃.Z ₀ ={Z _(L) +Z _(R)−tan θx·(q _(L) +q _(R))}/2  (11)tan θy={Z _(L) −Z _(R)−tan θx·(q _(L) −q _(R))}/(p _(R) −p _(L))  (12)

Incidentally, in the case of using other combinations of Z heads aswell, by using theoretical formulas (11) and (12), height Z₀ of wafertable WTB and rolling θy at reference point O can be computed. However,pitching θx uses the measurement results of another sensor system (inthe embodiment, interferometer system 118).

As shown in FIG. 24B, at the time of focus calibration and focusmapping, height Z of wafer table WTB and rolling θy at a center point O′of a plurality of detection points of the multipoint AF system (90 a, 90b) are measured, using four Z heads 72 a to 72 d. Z heads 72 a to 72 d,in this case, are respectively placed at position (X, Y)=(p_(a), q_(a)),(p_(b), q_(b)), (p_(a), q_(c)), (p_(d), q_(d)). As shown in FIG. 24B,these positions are set symmetric to center point O′=(Ox′, Oy′), or morespecifically, p_(a)=p_(b), p_(c)=p_(d), q_(a)=q_(c), q_(b)=q_(d), andalso (p_(a)+p_(c))/2=(p_(b)+p_(d))/2=Ox′,(q_(a)+q_(b))/2=(q_(c)+q_(d))/2=Oy′.

From average (Za+Zb)/2 of measurement values Za and Zb of Z head 72 aand 72 b, height Ze of wafer table WTB at a point e of position(p_(a)=p_(b), Oy′) can be obtained, and from average (Zc+Zd)/2 of themeasurement values Zc and Zd of Z heads 70 c and 70 d, height 2 f ofwafer table WTB at a point f of position (p_(c)=p_(d), Oy′) can beobtained. In this case, when the height of wafer table WTB at centerpoint O′ is expressed as Z₀, and the tilt (rolling) around the Y-axis isexpressed as θy, then, Ze and Zf follow theoretical formulas (13) and(14), respectively.Ze{=(Z _(a) +Z _(b))/2}=−tan θy·(p _(a) +p _(b)−2Ox′)/2+Z ₀  (13)Zf{=(Z _(c) +Z _(d))/2}=−tan θy·(p _(c) +p _(d)−2Ox′)/2+Z ₀  (14)

Accordingly, from theoretical formulas (13) and (14), height Z₀ of wafertable WTB and rolling θy at center point O′ can be expressed as in thefollowing formulas (15) and (16), using measurement values Za to Zd of Zheads 70 a to 70 d.

$\begin{matrix}{Z_{0} = {{\left( {{Ze} + {Zf}} \right)/2} = {\left( {{Za} + {Zb} + {Zc} + {Zd}} \right)/4}}} & (15) \\\begin{matrix}{{\tan\;\theta\; y} = {{- 2}{\left( {{Ze} - {Zf}} \right)/\left( {p_{a} + p_{b} - p_{c} - p_{d}} \right)}}} \\{= {{- \left( {{Za} + {Zb} - {Zc} - {Zd}} \right)}/\left( {p_{a} + p_{b} - p_{c} - p_{d}} \right)}}\end{matrix} & \left. (16) \right)\end{matrix}$

However, pitching θx uses the measurement results of another sensorsystem (in the embodiment, interferometer system 118).

As shown in FIG. 16, immediately after switching from servo control ofwafer stage WST by interferometer system 118 to servo control by encodersystem 150 (encoders 70A to 70F) and surface position measurement system180 (Z head systems 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅),because only two heads, Z heads 72 b and 72 d, face the corresponding Yscales 39Y₁ and 39Y₂, the Z and θy positions of wafer stage WST atcenter point O′ cannot be computed using formulas (15) and (16). In sucha case, the following formulas (17) and (18) are applied.Z ₀ ={Z _(b) +Z _(d)−tan θx·(q _(b) +q _(d)−2Oy′)}/2  (17)tan θy={Z _(b) −Z _(d)−tan θx·(q _(b) −q _(d))}/(p _(d) −p _(b))  (18)

Then, when wafer stage WST has moved in the +Z direction, andaccompanying this move, after Z heads 72 a and 72 c have faced thecorresponding Y scales 39Y₁ and 39Y₂, formulas (15) and (16) above areapplied.

As previously described scanning exposure to wafer W is performed, afterfinely driving wafer stage WST in the Z-axis direction and tiltdirection according to the unevenness of the surface of wafer W, andhaving adjusted the surface position of wafer W and the tilt (focusleveling) so that the exposure area IA portion on the surface of wafer Wmatches within the range of the depth of focus of the image plane ofprojection optical system PL. Therefore, prior to the scanning exposure,focus mapping to measure the unevenness (a focus map) of the surface ofwafer W is performed. In this case, as shown in FIG. 10B, the unevennessof the surface of wafer W is measured at a predetermined samplinginterval (in other words, a Y interval) while moving wafer stage WST inthe +Y direction, using the multipoint AF system (90 a, 90 b) with thesurface position of wafer table WTB (or to be more precise, thecorresponding Y scales 39Y₁ and 39Y₂) measured using Z heads 72 a to 72d serving as a reference.

To be specific, as shown in FIG. 24B, surface position Ze of wafer tableWTB at point e can be obtained from the average of surface positions Zaand Zb of Y scale 39Y₂, which is measured using Z heads 72 a and 72 b,and surface position Zf of wafer table WTB at point f can be obtainedfrom the average of surface positions Zc and Zd of Y scale 39Y₁, whichis measured using Z heads 72 c and 72 d. In this case, the plurality ofdetection points of the multipoint AF system and center O′ of thesepoints are located on a straight line ef parallel to the X-axis andconnecting point e and point f. Therefore, as shown in FIG. 10C, byusing a straight line expressed in the following formula (19) connectingsurface position Ze at point e (P1 in FIG. 10C) of wafer table WTB andsurface position Zf at point f (P2 in FIG. 10C) as a reference, surfaceposition Z_(0k) of the surface of wafer W at detection point X_(k) ismeasured, using the multipoint AF system (90 a, 90 b).Z(X)=−tan θy·X+Z ₀  (19)

However, Z₀ and tan θy can be obtained from formulas (17) and (18)above, using measurement results Za to Zd of Z heads 72 a to 72 d. Fromthe results of surface position Z_(Ok) that has been obtained,unevenness data (focus map) Z_(k) of the surface of wafer W can beobtained as in the following formula (20).Z _(k) =Z _(0k) −Z(X _(k))  (20)

At the time of exposure, by finely driving wafer stage WST in the Z-axisdirection and the tilt direction according to focus map. Z_(k) obtainedin the manner described above, the surface position of wafer W and thetilt are adjusted as is previously described. At the time of theexposure here, the surface position of wafer table WTB (or to be moreprecise, the corresponding Y scales 39Y₂ and 39Y₁) is measured, using Zheads 74 _(i) and 76 _(j) (i, j=1-5). Therefore, reference line Z(X) offocus map Z_(k) is set again. However, Z₀ and tan θy can be obtainedfrom formulas (11) and (12) above, using the measurement results Z_(L)and Z_(R) of Z heads 74 _(i) and 76 _(j) (i, j=1-5). From the proceduredescribed so far, the surface position of the surface of wafer W isconverted to Z_(k)+Z(X_(k)).

In the embodiment, the Z and θy positions of wafer stage WST arecomputed by measuring the surface position of (the reflection gratingformed on) Y scales 39Y₁ and 39Y₂, using Z heads 72 a to 72 d, 74 ₁ to74 ₅, and 76 ₁ to 76 ₅, and applying the measurement results to formulas(11) and (12). In this case, as a parameter of formulas (11) and (12), asetting position (or to be more precise, the XY position of themeasurement point) of the Z heads becomes necessary. Further, forexample, the measurement results of the Z heads include an error causedby the unevenness of Y scales 39Y₁ and 39Y₂. Therefore, an unevennessdata of Y scales 39Y₁ and 39Y₂ are to be made beforehand, themeasurement results are to be corrected using the data. Now, because theunevenness data will be made as a function of a two-dimensionalcoordinate (X, Y), the setting position of the Z head will be necessarywhen reading the necessary correction data from the unevenness data.

Incidentally, even if the design setting position of Z heads 72 a to 72d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅ was accurately known, the settingposition of the Z heads may change due to long hours of use and the likeof exposure apparatus 100. Accordingly, the setting position of the Zheads has to be measured regularly, and using the latest results themeasurement results of the Z heads have to be corrected, and the Z andθy positions of wafer stage WST also have to be computed.

In order to measure the setting position of Z heads 72 a to 72 d, 74 ₁to 74 ₅, and 76 ₁ to 76 ₅, for example, Y scales 39Y₃ and 39Y₄ are to beprepared on the upper surface of wafer table WTB as shown in FIG. 25A.However, for the convenience of the drawings, in FIGS. 25A and 25B, thewidth of Y scales 39Y₃ and 39Y₄ in the Y-axis direction (L1 describedlater on), and the separated distance (L2 described later on) of Yscales 39Y₃ and 39Y₄ with Y scales 39Y₁ and 39Y₂ are illustrated largerthan the actual state.

Y scales 39Y₃ and 39Y₄ are configured of a reflection grating similar toY scales 39Y₁ and 39Y₂ serving as a measurement subject surface of the Zheads, and as it can be seen from the outline shown in FIG. 26A, Yscales 39Y₃ and 39Y₄ are arranged on the +Y end of wafer table WTB,distanced from Y scales 39Y₁ and 39Y₂ by a predetermined separateddistance L2. In this case, the predetermined separated distance L2 andwidth L1 of Y scales 39Y₃ and 39Y₄ in the Y-axis direction are setlarger than the broadening of the cross-section of probe beam LB, whichis around several μm. Incidentally, the width of Y scales 39Y₃ and 39Y₄in the X-axis direction is set equal to the width of Y scales 39Y₁ and39Y₂.

Main controller 20 measures the setting position of Z heads 72 a to 72d, 74₁ to 74₅, and 76 ₁ to 76 ₅, using Y scales 39Y₃ and 39Y₄ in themanner described below. In this case, two representative heads arechosen, which are; one head from Z heads 72 a, 72 b, and 74 ₁ to 74 ₅,and one head from Z heads 72 c, 72 d, and 76 ₁ to 76 ₅. And, the settingposition of the two Z heads is measured. In FIG. 25A, as therepresentative heads, Z heads 74 ₃ and 76 ₃ are selected.

Incidentally, during the measurement, wafer stage WST is to maintain areference attitude. More specifically, wafer stage WST is positioned ata reference position regarding directions of four degree of freedom (Z,θx, θy, θz). Then, the θx and θz positions are monitored using Yinterferometer 16, and the Z and θy positions are monitored using Zinterferometers 43A and 43B, and control is performed so that waferstage WST is not displaced in the directions of four degrees of freedom.And, the X and Y positions are monitored using X interferometer 127 andY interferometer 16, respectively, and drive control of wafer stage WSTin directions of two degrees of freedom (X, Y) is performed.

Y scales 39Y₄ and 39Y₃ are scanned, using Z heads 74 ₃ and 76 ₃. Duringthis scanning, Z heads 74 ₃ and 76 ₃ are shifted to a scale servo state.More specifically, servo control is performed so that a focal point ofprobe beam LB of Z heads 74 ₃ and 76 ₃ coincides with the surfaceposition of Y scales 39Y₃ and 39Y₄ predicted from the measurementresults of interferometer system 118. In this state, using focus sensorFS within the Z head, intensity of the reflected light of probe beam LB,that is, sum I′ of the intensity of the reflected lights received byeach of the four detection areas a, b, c, and d of tetrameric lightreceiving element ZD, is measured.I′=(Ia+Ic)+(Ib+Id)  (21)

The expression is similar to formula (7).

Wafer stage WST is moved in the Y-axis direction, and using Z heads 74 ₃and 76 ₃, Y scales 39Y₄ and 39Y₃ are scanned in the Y-axis direction. Aswafer stage WST moves in the +Y direction, a scanning point of Z heads74 ₃ and 76 ₃, that is, an irradiation section of probe beam LB, entersthe scanning area of Y scales 39Y₄ and 39Y₃ (the area where thereflection grating is formed) from the +Y side of the scales. In FIGS.25A and 26A, the irradiation section of probe beam LB of Z heads 74 ₃and 76 ₃ is located within the scanning area of Y scales 39Y₄ and 39Y₃.Furthermore, when wafer stage WST moves to the +Y direction, theirradiation section of probe beam LB of Z heads 74 ₃ and 76 ₃respectively move off to the spacing area in between Y scales 39Y₄ and39Y₃ and Y scales 39Y₂ and 39Y₁.

With the relative displacement of the irradiation section of probe beamLB of Z heads 74 ₃ and 76 ₃ described above and Y scales 39Y₄ and 39Y₃in the Y-axis direction, output signal I′ of focus sensor FS in theformula (21) changes as in curve S1 shown in FIG. 26B. In this case, ata Y area where irradiation section of the probe beam LB enters/exits thescanning area of Y scales 39Y₄ and 39Y₃, output signal I′ changes, andat the Y area where probe beam LB is completely within the scanningarea, output signal I′ becomes constant.

Accordingly, by a midpoint Y0 of Y positions Y1 and Y2 of the twointersecting points of output signal I′ and a predetermined slice level(a threshold value) SL, the Y setting position of Z heads 74 ₃ and 76 ₃can be determined.

Incidentally, even in the case when output signal I′ of focus sensor FSis weak as in curve S2 shown in FIG. 26B, although Y positions Y1′ andY2′ where output signal I′ becomes equal to slice level (thresholdvalue) SL change, midpoint Y0 of the Y positions does not change.Accordingly, the setting position of Z heads 74 ₃ and 76 ₃ can bedetermined precisely. Further, the slice level (threshold value) can beset at half maximum I′max/2 of the maximum output I′max of output signalI′. In such a case, midpoint Y0 can be determined even when maximumoutput I′max of the focus sensor does not reach threshold value SL.

Similarly, by scanning Y scales 39Y₄ and 39Y₃ in the X-axis directionusing Z heads 74 ₃ and 76 ₃, the X setting position of Z heads 74 ₃ and76 ₃ is decided.

Incidentally, in the case Y scales 39Y₄ and 39Y₃ cannot be used, or whenthe measurement using Y scales 39Y₄ and 39Y₃ described above does notfunction, an end section of the diffraction grating of Y scales 39Y₂ and39Y₁ (or an end section of the diffraction grating of Y scales 39Y₄ and39Y₃) is used.

As shown in FIG. 25B, the −Y end section of Y scales 39Y₂ and 39Y₁ isscanned, using Z heads 74 ₃ and 76 ₃ selected as the representativeheads. In this case, wafer stage WST is moved to the +Y direction, andthe −Y end of Y scales 39Y₂ and 39Y₁ are scanned in the Y-axisdirection. On this scanning, output signal I′ (formula (21)) of focussensor FS changes like curve S shown in FIG. 26C. Therefore, thresholdvalue SL is set to half maximum I′max/2 of the maximum output I′max, andfrom Y position Y0′, which is the intersecting point of output signal I′(formula (21)) and slice level (threshold value) SL, the Y settingposition of Z heads 74 ₃ and 76 ₃ is decided.

Similarly, by scanning the ±X end section of Y scales 39Y₂ and 39Y₁ (Yscales 39Y₄ and 39Y₃ are also acceptable) using Z heads 74 ₃ and 76 ₃ inthe X-axis direction, the X setting position of Z heads 74 ₃ and 76 ₃ isdecided.

The setting position for the remaining heads is also measured in amanner similar to representative heads 74 ₃ and 76 ₃. In this case,relative position with the setting position of the representative headsserving as a reference can be measured.

In the manner described above, main controller 20 measures the settingposition of Z heads 72 a to 72 d, 74 ₁ to 74 ₅, and 76 ₁ to 76 ₅ ofsurface position measurement system 180 regularly, and stores themeasurement results in memory 34 or in an internal memory And whendriving wafer stage WST, main controller 20 reads the necessarycorrection data from the unevenness data using the latest results andcorrects the measurement results of the Z heads, and further controlsthe position of wafer stage WST in the Z-axis direction and the θydirection while computing the (Z, θy) position of wafer stage WST.

Incidentally, so far, in order to simplify the description, while maincontroller 20 performed the control of each part of the exposureapparatus including the control of the stage system (such as reticlestage RST and wafer stage WST), interferometer system 118, encodersystem 150 and the like, as a matter of course, at least a part of thecontrol of main controller 20 described above can be performed shared bya plurality of controllers. For example, a stage controller whichperforms operations such as the control of the stage, switching of theheads of encoder system 150 and surface position measurement system 180can be arranged to operate under main controller 20. Further, thecontrol that main controller 20 performs does not necessarily have to berealized by hardware, and main controller 20 can realize the control bysoftware according to a computer program that sets each operation ofsome controllers that perform the control sharing as previouslydescribed.

As discussed in detail above, according to exposure apparatus 100related to the embodiment, wafer stage WST is moved along an XY plane bymain controller 20, and during the movement of wafer stage WST,positional information of the wafer stage WST surface in the z-axisdirection orthogonal to the XY plane is measured using a plurality of Zheads of surface position measurement system 180, and based on themeasurement information and positional information (setting positioninformation) of at least one Z head within a surface parallel to the XYplane used in the measurement, wafer stage WST is driven in the Z-axisdirection and the θy direction. Accordingly, it becomes possible todrive wafer stage WST in the Z-axis direction and the θy direction sothat the position measurement error of wafer stage WST in the Z-axisdirection and the θy direction due to the position error (an error fromthe design value) of the Z heads in a plane parallel to the XY plane iscancelled out.

Further, according to exposure apparatus 100 related to the embodiment,by transferring and forming the pattern of reticle R in each shot areaon wafer W mounted on wafer stage WST (wafer table WTB) whose positionin the Z-axis direction (and in the θy direction) is controlled withhigh precision in the manner described above, it becomes possible toform a pattern on each shot area on wafer W with good precision.

Further, according to exposure apparatus 100 related to the embodiment,by performing the focus leveling control of the wafer with high accuracyduring scanning exposure using the Z heads without measuring the surfaceposition information of the wafer surface during exposure, based on theresults of focus mapping performed beforehand, it becomes possible toform a pattern on wafer W with good precision. Furthermore, in theembodiment, because a high-resolution exposure can be realized by liquidimmersion exposure, a fine pattern can be transferred with goodprecision on wafer W also from this viewpoint.

Incidentally, in the embodiment above, when focus sensor FS of each Zhead performs the focus-servo previously described, the focal point maybe on the cover glass surface protecting the diffraction grating surfaceformed on Y scales 39Y₁ and 39Y₂, however, it is desirable for the focalpoint to be on a surface further away than the cover glass surface, suchas, on the diffraction grating surface. With this arrangement, in thecase foreign material (dust) such as particles is on the cover glasssurface and the cover glass surface becomes a surface which is defocusedby the thickness of the cover glass, the influence of the foreignmaterial is less likely to affect the Z heads.

In the embodiment above, the surface position measurement system whichis configured having a plurality of Z heads arranged exterior to wafertable WTB (the upper part) in the operating range (a range where thedevice moves in the actual sequence in the movement range) of wafertable WTB and detects the Z position of the wafer table WTB (Y scales39Y₁ and 39Y₂) surface with each Z head was employed, however, thepresent invention is not limited to this. For example, a plurality of Zheads can be placed on a movable body (for example, wafer stage WST inthe case of the embodiment above) upper surface, and a detection device,which faces the heads and has a reflection surface arranged outside themovable body that reflects the probe beam from the Z heads, can beemployed, instead of surface position detection system 180.

For example, in the embodiment above, an example has been describedwhere the encoder system is employed that has a configuration where agrid section (a Y scale and an X scale) is arranged on a wafer table (awafer stage), and X heads and Y heads facing the grid section are placedexternal to the wafer stage, however, the present invention is notlimited to this, and an encoder system which is configured having anencoder head arranged on the movable body and has a two-dimensional grid(or a linear grid section having a two-dimensional placement) facing theencoder heads placed external to the wafer stage can also be adopted. Inthis case, when Z heads are also to be placed on the movable body uppersurface, the two-dimensional grid (or the linear grid section having atwo-dimensional placement) can also be used as a reflection surface thatreflects the probe beam from the Z heads.

Further, in the embodiment above, the case has been described where eachZ head is equipped with sensor main section ZH (the first sensor) whichhouses focus sensor FS and is driven in the Z-axis direction by thedrive section (not shown), measurement section ZE (the second sensor)which measures the displacement of the first sensor (sensor main sectionZH) in the Z-axis direction, and the like as shown in FIG. 7, however,the present invention is not limited to this. More specifically, withthe Z head (the sensor head), the first sensor itself does notnecessarily have to be movable in the Z-axis direction, as long as apart of the member configuring the first sensor (for example, the focussensor previously described) is movable, and the part of the membermoves according to the movement of the movable body in the Z-axisdirection so that the optical positional relation (for example, aconjugate relation of the light receiving elements within the firstsensor with the photodetection surface (detection surface)) of the firstsensor with the measurement object surface is maintained. In such acase, the second sensor measures the displacement in the movementdirection from a reference position of the moving member. As a matter ofcourse, in the case a sensor head is arranged on the movable body, themoving member should be moved so that the optical positional relation ofthe measurement object of the first sensor, such as, for example, thetwo-dimensional grid described above (or the linear grid section havinga two-dimensional placement) and the like with the first sensor ismaintained, according to the position change of the movable body in adirection perpendicular to the two-dimensional plane.

Further, in the embodiment above, while the case has been describedwhere the encoder head and the Z head are separately arranged, besidessuch a case, for example, a head that has both functions of the encoderhead and the Z head can be employed, or an encoder head and a Z headthat have a part of the optical system in common can be employed, or acombined head which is integrated by arranging the encoder head and theZ head within the same housing can also be employed.

Incidentally, in the embodiment above, while the lower surface of nozzleunit 32 and the lower end surface of the tip optical element ofprojection optical system PL were on a substantially flush surface, aswell as this, for example, the lower surface of nozzle unit 32 can beplaced nearer to the image plane (more specifically, to the wafer) ofprojection optical system PL than the outgoing surface of the tipoptical element. That is, the configuration of local liquid immersionunit 8 is not limited to the configuration described above, and theconfigurations can be used, which are described in, for example, EPPatent Application Publication No. 1 420 298, the pamphlet ofInternational Publication No. 2004/055803, the pamphlet of InternationalPublication No. 2004/057590, the pamphlet of International PublicationNo. 2005/029559 (the corresponding U.S. Patent Application PublicationNo. 2006/0231206), the pamphlet of International Publication No.2004/086468 (the corresponding U.S. Patent Application Publication No.2005/0280791), the U.S. Pat. No. 6,952,253, and the like. Further, asdisclosed in the pamphlet of International Publication No. 2004/019128(the corresponding U.S. Patent Application Publication No.2005/0248856), the optical path on the object plane side of the tipoptical element may also be filled with liquid, in addition to theoptical path on the image plane side of the tip optical element.Furthermore, a thin film that is lyophilic and/or has dissolutionpreventing function may also be formed on the partial surface (includingat least a contact surface with liquid) or the entire surface of the tipoptical element. Incidentally, quartz has a high affinity for liquid,and also needs no dissolution preventing film, while in the case offluorite, at least a dissolution preventing film is preferably formed.

Incidentally, in the embodiment above, pure water (water) was used asthe liquid, however, it is a matter of course that the present inventionis not limited to this. As the liquid, liquid that is chemically stable,having high transmittance to illumination light IL and safe to use, suchas a fluorine-containing inert liquid may be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 can be used. As this typeof liquid, for example, a predetermined liquid having C—H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of these liquids may be used, or aliquid obtained by adding (mixing) at least one of these liquids to(with) pure water may be used. Alternatively, as the liquid, a liquidobtained by adding (mixing) base or acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄²⁻, or PO₄ ²⁻ to (with) pure water can be used. Moreover, a liquidobtained by adding (mixing) particles of Al oxide or the like to (with)pure water can be used. These liquids can transmit ArF excimer laserlight. Further, as the liquid, liquid, which has a small absorptioncoefficient of light, is less temperature-dependent, and is stable to aprojection optical system (tip optical member) and/or a photosensitiveagent (or a protection film (top coat film), an antireflection film, orthe like) coated on the surface of a wafer, is preferable. Further, inthe case an F₂ laser is used as the light source, fomblin oil can beselected. Further, as the liquid, a liquid having a higher refractiveindex to illumination light IL than that of pure water, for example, arefractive index of around 1.6 to 1.8 may be used. As the liquid,supercritical fluid can also be used. Further, the tip optical elementof projection optical system PL may be formed by quartz (silica), orsingle-crystal materials of fluoride compound such as calcium fluoride(fluorite), barium fluoride, strontium fluoride, lithium fluoride, andsodium fluoride, or may be formed by materials having a higherrefractive index than that of quartz or fluorite (e.g. equal to orhigher than 1.6). As the materials having a refractive index equal to orhigher than 1.6, for example, sapphire, germanium dioxide, or the likedisclosed in the pamphlet of International Publication No. 2005/059617,or kalium chloride (having a refractive index of about 1.75) or the likedisclosed in the pamphlet of International Publication No. 2005/059618can be used.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery unit, a recovery pipeor the like.

Incidentally, in the embodiment above, the case has been described wherethe exposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, but can also beemployed in a dry type exposure apparatus that performs exposure ofwafer W without liquid (water).

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Further, the present invention can also be applied toa reduction projection exposure apparatus by a step-and-stitch methodthat synthesizes a shot area and a shot area, an exposure apparatus by aproximity method, a mirror projection aligner, or the like. Moreover,the present invention can also be applied to a multi-stage type exposureapparatus equipped with a plurality of wafer stage WSTs, as is disclosedin, for example, the U.S. Pat. No. 6,590,634, the U.S. Pat. No.5,969,441, the U.S. Pat. No. 6,208,407 and the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatodioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Moreover, exposure area IA towhich illumination light IL is irradiated via projection optical systemPL is an on-axis area that includes optical axis AX within the field ofprojection optical system PL. However, for example, as is disclosed inthe pamphlet of International Publication No. 2004/107011, exposure areaIA may also be an off-axis area that does not include optical axis AX,similar to a so-called inline type catodioptric system, in part of whichan optical system (catoptric system or catodioptric system) that hasplural reflection surfaces and forms an intermediate image at least onceis arranged, and which has a single optical axis. Further, theillumination area and exposure area described above are to have arectangular shape. However, the shape is not limited to rectangular, andcan also be circular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr₂ laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm) or an i-line (wavelength: 365 nm) can also be used.Further, a harmonic wave generating unit of a YAG laser or the like canalso be used. Besides the sources above, as is disclosed in, forexample, the pamphlet of International Publication No. 99/46835 (thecorresponding U.S. Pat. No. 7,023,610), a harmonic wave, which isobtained by amplifying a single-wavelength laser beam in the infrared orvisible range emitted by a DFB semiconductor laser or fiber laser asvacuum ultraviolet light, with a fiber amplifier doped with, forexample, erbium (or both erbium and ytteribium), and by converting thewavelength into ultraviolet light using a nonlinear optical crystal, canalso be used.

Further, in the embodiment above, illumination light IL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm can be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOR or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (forexample, 13.5 nm) and the reflective mask has been developed. In the EUVexposure apparatus, the arrangement in which scanning exposure isperformed by synchronously scanning a mask and a wafer using a circulararc illumination can be considered, and therefore, the present inventioncan also be suitably applied to such an exposure apparatus. Besides suchan apparatus, the present invention can also be applied to an exposureapparatus that uses charged particle beams such as an electron beam oran ion beam.

Further, in the embodiment above, a transmissive type mask (reticle),which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed, is used. Instead of this reticle, however, as is disclosed in,for example, U.S. Pat. No. 6,778,257, an electron mask (which is alsocalled a variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed can also be used.

Further, as is disclosed in, for example, the pamphlet of InternationalPublication No. 2001/035168, the present invention can also be appliedto an exposure apparatus (lithography system) that forms line-and-spacepatterns on a wafer by forming interference fringes on the wafer.

Moreover, as disclosed in, for example, U.S. Pat. No. 6,611,316, thepresent invention can also be applied to an exposure apparatus thatsynthesizes two reticle patterns via a projection optical system andalmost simultaneously performs double exposure of one shot area by onescanning exposure.

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The use of the exposure apparatus is not limited only to the exposureapparatus for manufacturing semiconductor devices, but the presentinvention can also be widely applied, for example, to an exposureapparatus for transferring a liquid crystal display device pattern ontoa rectangular glass plate, and an exposure apparatus for producingorganic ELs, thin-film magnetic heads, imaging devices (such as CCDs),micromachines, DNA chips, and the like. Further, the present inventioncan be applied not only to an exposure apparatus for producingmicrodevices such as semiconductor devices, but can also be applied toan exposure apparatus that transfers a circuit pattern onto a glassplate or silicon wafer to produce a mask or reticle used in a lightexposure apparatus, an EUV exposure apparatus, an X-ray exposureapparatus, an electron-beam exposure apparatus, and the like.

Incidentally, the movable body drive system and the movable body drivemethod of the present invention can be applied not only to the exposureapparatus, but can also be applied widely to other substrate processingapparatuses (such as a laser repair apparatus, a substrate inspectionapparatus and the like) or to apparatuses equipped with a movable bodysuch as a stage that moves within a two-dimensional plane such as aposition setting apparatus of a sample or a wire bonding apparatus inother precision machines.

Incidentally, the disclosures of the various publications(descriptions), the pamphlets of the International Publications, and theU.S. patent application Publication descriptions and the U.S. Patentdescriptions that are cited in the embodiment above and related toexposure apparatuses and the like are each incorporated herein byreference.

Semiconductor devices are manufactured through the following steps: astep where the function/performance design of the wafer is performed, astep where a wafer is made using silicon materials, a lithography stepwhere the pattern formed on the reticle (mask) by the exposure apparatus(pattern formation apparatus) in the embodiment previously described istransferred onto a wafer, a development step where the wafer that hasbeen exposed is developed, an etching step where an exposed member of anarea other than the area where the resist remains is removed by etching,a resist removing step where the resist that is no longer necessary whenetching has been completed is removed, a device assembly step (includingprocesses such as a dicing process, a bonding process, and a packagingprocess), inspection steps and the like.

By using the device manufacturing method of the embodiment describedabove, because the exposure apparatus (pattern formation apparatus) inthe embodiment above and the exposure method (pattern formation method)thereof are used in the exposure step, exposure with high throughput canbe performed while maintaining the high overlay accuracy. Accordingly,the productivity of highly integrated microdevices on which finepatterns are formed can be improved.

While the above-described embodiment of the present invention is thepresently preferred embodiment thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiment without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

1. A movable body drive method in which a movable body is drivensubstantially along a two-dimensional plane, the method comprising: adrive process in which the movable body is moved along a predetermineddirection parallel to the two-dimensional plane, and during the movementof the movable body, positional information of the movable body in adirection orthogonal to the two-dimensional plane is measured using aplurality of sensor heads of a position measurement system, and based onthe measured positional information of the movable body and positionalinformation within a plane parallel to the two-dimensional plane of atleast one sensor head used in measurement of the information, themovable body is driven in at least a tilt direction with respect to thetwo-dimensional plane; and a measuring process in which, prior to thedrive process, the movable body is moved parallel to the two-dimensionalplane, and during the movement, measurement information of the at leastone sensor head is acquired, and thereby positional information of thesensor head within the plane corresponding to the measurementinformation is measured.
 2. The movable body drive method according toclaim 1 wherein in the drive process, the movable body is driven in thetilt direction with respect to the two-dimensional plane, based furtheron information of an error component specific to each sensor head usedto measure the positional information of the movable body.
 3. Themovable body drive method according to claim 1 wherein the measuringprocess includes a first head position measuring process in which themovable body is moved in a first direction within the two-dimensionalplane so that the movable body passes through a detection area of asensor corresponding to the sensor head of the position measurementsystem, and based on a first measurement value of a first measuringdevice which measures positional information of the movable body in thefirst direction and a detection signal of the sensor corresponding tothe first measurement value that are obtained during the movement, aposition of the sensor head in the first direction is computed.
 4. Themovable body drive method according to claim 3 wherein the measuringprocess further includes a second head position measuring process inwhich the movable body is moved in a second direction orthogonal to thefirst direction within the two-dimensional plane so that the movablebody passes through the detection area of the sensor, and based on asecond measurement value of a second measuring device which measurespositional information of the movable body in the second direction and adetection signal of the sensor corresponding to the second measurementvalue that are obtained during the movement, a position of the sensorhead in the second direction is computed.
 5. The movable body drivemethod according to claim 4 wherein the sensor head is arranged externalto the movable body, and the detection area of the sensor includes afirst measurement area and a second measurement area on the movablebody.
 6. The movable body drive method according to claim 5 wherein thesecond measurement area includes a pattern for positioning in the seconddirection.
 7. The movable body drive method according to claim 5 whereinthe first measurement area has at least a part which is common with thesecond measurement area, and the part which is common includes a patternfor positioning in the first and second directions.
 8. The movable bodydrive method according to claim 3 wherein the sensor head is arrangedexternal to the movable body, and the detection area of the sensorincludes a pattern for positioning in the first direction.
 9. A patternformation method, comprising: a mount process that includes mounting anobject on a movable body that can move along a movement plane; and adrive process that includes driving the movable body by the movable bodydrive method according to claim 1, to form a pattern on the object. 10.A device manufacturing method, comprising: a pattern formation processthat includes forming a pattern on a substrate by the pattern formationmethod according to claim
 9. 11. An exposure method in which a patternis formed on an object by an irradiation of an energy beam, the methodcomprising: for relative movement of the energy beam and the object,driving a movable body on which the object is mounted, by the movablebody drive method according to claim
 1. 12. A measuring method thatmeasures positional information within a plane parallel to atwo-dimensional plane of a sensor head, which is equipped in a positionmeasurement system that measures positional information in a tiltdirection with respect to the two-dimensional plane of a movable bodythat moves substantially along the two-dimensional plane and which isused to measure positional information of the movable body in adirection orthogonal to the two-dimensional plane, the methodcomprising: a first head position measuring process in which the movablebody is moved in a first direction within the two-dimensional plane sothat the movable body passes through a detection area of a sensorcorresponding to the sensor head of the position measurement system, andbased on a first measurement value of a first measuring device arrangedseparately from the position measurement system and measures positionalinformation of the movable body in the first direction and a detectionsignal of the sensor corresponding to the first measurement value thatare obtained during the movement, a position of the sensor head in thefirst direction is computed.
 13. The measuring method according to claim12, the method further comprising: a second head position measuringprocess in which the movable body is moved in a second directionorthogonal to the first direction within the two-dimensional plane sothat the movable body passes through the detection area of the sensor,and based on a second measurement value of the second measuring devicewhich measures positional information of the movable body in the seconddirection and a detection signal of the sensor corresponding to thesecond measurement value that are obtained during the movement, aposition of the sensor head in the second direction is computed.
 14. Themeasuring method according to claim 13 wherein the sensor head isarranged external to the movable body, and the detection area of thesensor includes a first measurement area and a second measurement areaon the movable body.
 15. The measuring method according to claim 14wherein the second measurement area includes a pattern for positioningin the second direction.
 16. The measuring method according to claim 14wherein the first measurement area has at least a part which is commonwith the second measurement area, and the part which is common includesa pattern for positioning in the first and second directions.
 17. Themeasuring method according to claim 12 wherein the sensor head isarranged external to the movable body, and the detection area of thesensor includes a pattern for positioning in the first direction.
 18. Amovable body drive system in which a movable body is drivensubstantially along a two-dimensional plane, the system comprising: aposition measurement system that has a plurality of heads which isplaced two-dimensionally within a plane parallel to the two-dimensionalplane and measures positional information of the movable body in adirection orthogonal to the two-dimensional plane; a drive device thatmoves the movable body along a predetermined direction parallel to thetwo-dimensional plane, and during the movement of the movable body,measures positional information of the movable body in the directionorthogonal to the two-dimensional plane using the plurality of sensorheads of the position measurement system, and based on the measuredpositional information of the movable body and positional informationwithin a plane parallel to the two-dimensional plane of at least onesensor head used in measurement of the information, drives the movablebody in a tilt direction with respect to the two-dimensional plane; anda measurement device which measures positional information related tothe first direction and/or the second direction in the two-dimensionalplane of the movable body, wherein the positional information of the atleast one sensor head is based on the positional information of themovable body of when the at least one sensor head generates an outputaccording to a position of the movable body in the direction orthogonalto the two-dimensional plane.
 19. The movable body drive systemaccording to claim 18 wherein the drive device drives the movable bodyin a direction orthogonal to the two-dimensional plane and a tiltdirection with respect to the two-dimensional plane, based further oninformation of an error component specific to each sensor head used tomeasure positional information of the movable body.
 20. A patternformation apparatus, comprising: a movable body on which an object ismounted, and which is movable along a movement plane holding the object;and a body drive system according to claim 18 which drives the movablebody for pattern formation to the object.
 21. An exposure apparatus thatforms a pattern on an object by an irradiation of an energy beam, theapparatus comprising: a patterning device that irradiates the energybeam on the object; and a movable body drive system according to claim18, whereby the movable body drive system drives the movable body onwhich the object is mounted for relative movement of the energy beam andthe object.
 22. A position measurement system which measures positionalinformation of a movable body that moves substantially along atwo-dimensional plane, the system comprising: a plurality of sensorheads which are installed at a plurality of positions that can face thetwo-dimensional plane, facing the movable body that moves substantiallyalong the two-dimensional plane and generating an output according to aposition of the movable body in a direction orthogonal to thetwo-dimensional plane; and a first measurement device which measuresfirst positional information related to a first direction in thetwo-dimensional plane of the movable body, wherein at least tiltinformation with respect to the two-dimensional plane of the movablebody is detected, using an output from at least one of the plurality ofsensor heads, and information related to a setting position of the atleast one sensor head on a plane substantially parallel to the twodimensional plane, and the information related to the setting positionof the at least one sensor head is obtained, using the first positionalinformation of the movable body of when the at least one sensor headgenerates the output.
 23. The position measurement system according toclaim 22, the system further comprising: a second measurement devicewhich measures second positional information related to a seconddirection perpendicular to the first direction within thetwo-dimensional plane of the movable body, wherein the informationrelated to the setting position of the at least one sensor head isobtained, using the second positional information of the movable body ofwhen the at least one sensor head generates the output.
 24. The positionmeasurement system according to claim 22 wherein the plurality of sensorheads is placed two-dimensionally within a plane parallel to thepredetermined two-dimensional plane.